Books Recommended & Reviews for Civil Engineering

BOOKS RECOMMENDED FOR CIVIL ENGINEERING & REVIEWS

There are a lot of books available for each subject and each writer has its own way of narration and telling the subject in depth which can't be suitable for every student.

Here is a list of some books & reviews which will help you in choosing books required. 

BUILDING SCIENCE 

Textbooks :
1. Concrete Technology by Neville, A. M. & Brooks, J. J. Pearson Education
2. Civil Engineering Materials by Jackson, N. & Dhir, R. K, ELBS.
3. Building Construction by S. C. Renewal, Character publishing house Amend 1993
4. Civil Engineering Materials, TTTI Chandigarh
5. Construction Technology by Tony Bryan, Wiley
6. Advance Concrete Technology by Zogjin Li, Wiley
7. Building materials by Rangwala
8. Building Construction by Rangwala
9. Building materials by S.K. Duggal
Reference Books :
1. “Construction Technology - Volumes 1 and 2, 2^nd Edition” by R. Crudely, Longman, UK
2. Building Construction – volumes 1,2,3, and 4, 5th Edition by W. B.McKay. Orient Longman UK 1993
3. “Materials for civil and construction Engineers” by Michael S. Mamlouk and JOHN P. Zaniewski, Addison Longman Inc. USA
4. “Smart structure: Analysis and Design” by A. V. Srinivasan and D. M. McFarland, Cambridge“ University UK, 2001.
[Engineers’ Forum Reviews: Building construction & material by Rangwala may be used for semester prep.
others books may be consulted for advanced studies.  Books by Duggal is a better book for preparation of competitive exams like IES]

SURVEYING (FIELD MEASUREMENT)

1. Surveying vol I and II by B. C Punmia, A. K Jain and A. K. Jain Laxmi Publications (P) Ltd., New Delhi.
2. Surveying, vol. I and II by K. R. Arora, Standard Book House, Delhi
3. Surveying: Theory and Practice by R. E. Davis, F. S. Foote and J. W. Kelly, McGraw Hill Book company
4. Surveying and Engineering by Paul Watson, Wiley.
[Engineers’ Forum Reviews:  surveying by B.C. Punmia & Surveying by K.R. Arora is standard books with clear language and well-detailed theory. Surveying by B.C Punmia contains a collection of illustrative pictures of various instruments used in surveying which works as a nice reference ]

ADVANCED SURVEYING 

Text Books:
1. Geodesy by G.L Hosmer, John Wiley & Sons, New York.
2. Surveying vol. II and III by B.C. Punmia, A.K. Jain, Laxmi Publications (p) Ltd. New Delhi.
3. Surveying, vol. II and III by K.R. Arora, Standard Book House, Delhi.
4. The Elements of Astronomy for surveyors by J.B. Mackie, Charles Griffin and Company Ltd., High Wycombe, England.
5. Electromagnetic Distance Measurement by C.D. Burnside, Crosby Lockwood and son Ltd., London.

ENGINEERING GEOLOGY 

Text Books:
1.ENGINEERING and GENERAL GEOLOGY by Prabin Singh Katson publication
2.Principles of Engineering Geology by Johnston. R. B. and DeGraff. J. V., John Wiley and Sons, New York.
3. Fundamental of Engineering Geology by Waltham, T., Spon Press, London.
4. A Textbook of Engineering and General Geology by Singh. P., S. K. Kataria and Sons, New Delhi.
5. A Textbook of Geology by Mukherjee P. K., Te world press Pvt. Ltd., Kolkata.
6. Engineering Geology by D V Reddy, Vikash Publishing House Pvt. Ltd.
7. Element of Mineralogy in Engineering Geology by Read, H. H. Rutley’s, CBS Publisher.
8. Experiments in Engineering Geology by Gokhale, K. V. G. K. and Roa, D. M., Tata McGraw Hill.
[Engineers’ Forum Reviews: Engg. Geology by Prabin-written in simple and illustrative language suitable for semester preparations, others book may be considered as a reference book]

MECHANICS OF SOLID-1 

Text Books :
1. Mechanics of Solids by E.P.Popov, Pearson Education Pub.
2. Solid Mechanics by S.M.A. Kazimi, Tata McGraw Hill, New Delhi.
3. Strength of Materials by Ryder, G.H., Macmillan Press Ltd.
4. Solid Mechanics by Bhavikatti Vikash Publishing House Pvt. Ltd.
5. strength of materials by RK Bansal
6. SOM by Sadhu Singh
[Engineers’ Forum Reviews: SOM by R.K. Bansal & SOM by Bhavikatti-written in very simple language suitable for beginers& semester prep.
SOM by Kazimi- a bit advanced and in-depth recommended for further reading]

MECHANICS OF SOLID-II 

Text Books :

1. Advanced Mechanics of Materials by A.P. Boresi and O.M. Sidebottom, Fifth Edition, Wiley, Singapore.

2. Mechanics of Solid, Singh by A.K., PHI, New Delhi.

3. Strength of Materials Vol. 2 by S.P. Timoshenko, CBS Publishers, Delhi.

[Engineers’ Forum Reviews: SOM by Timoshenko is a standard book which is written in clear language starting from basics to a advance level]

FLUID MECHANICS 

Reference Book/ Text Books:
1. Fluid Mechanics by V.L.Streeter, E.B. and Wylie, McGraw Hill.
2. Fluid Mechanics by Fox & McDonald, John Wiley.
3. Fluid Mechanics by Munson, John Wiley.
4. Fluid Mechanics by F.M. White.
5. Fluid Mechanics with Engineering Application by R.L. Daugherthy, J.B. Franzini, E.J. Finnermore; McGraw Hill, International Ed.
6. I.H. Shames by Fluid Mechanics, PHI.
7. fluid mechanics by R.K Bansal
[Engineers’ Forum Reviews: for semester prepration R K Bansal my be good with  a very easy language as it focuses on basic concepts other books may be considered a bit advanced]

SOIL MECHANICS – I

Text Books :
1. A Text-Book of Soil Mechanics and Foundation Engineering by V.N.S. Murthy, Saikripa Technical consultants, Bangalore.
2. Geotechnical Engineering by S. K. Gulati et. al., TMH Publication Co. Ltd., New Delhi
3. Basic and applied Soil Mechanics by Gopal Ranjan and A. S. R. Rao, Wiley Eastern Ltd., New Delhi.
4. Soil Mechanics and Foundation Engineering by K. R. Arora, Standard Pub. and Dist., Delhi
5. soil mechanics by B.C Punamia
Reference Books :
1. Soil Mechanics in Engineering Practice by Terzaghi and Pech, John Wiley and Sons Inc New York.
2. Soil Mechanics by Lamb and Whitman, Wiley Eastern Pvt. Ltd., New Delhi.
3. Fundamentals of Soil Mechanics by Taylor, John Wiley and Sons Inc New Delhi.
[Engineers’ Forum Reviews: soil mechanics by V.N.S Murthy,Gopal ranjan , B.C punamia may be used for semester prep.]

HYDRAULICS & OPEN CHANNEL FLOW 

Text Books :
1. Flow in Open Channels by K.G. Ranga, Raju, Tata McGraw Hill Publication Co. Ltd., New Delhi.
2. Flow in Open Channel by K.Subramanya, Tata McGraw Hill Publication Co. Ltd., New Delhi.
3. Fluid Mechanics by A. K. Jain, Khanna Publishers, Second Edition, Delhi-6, 1980
Reference Books :
1. Open Channel Hydraulics by V.T.Chow, McGraw Hill International, New York, 1959.
2. Foundation of Fluid Mechanics by S.W. Yuan, Tata McGraw Hill Publication Co. Ltd., New Delhi.
3. Open Channel Hydraulics by R.H. French, McGraw Hill Book co., New York, 1986.
4. Boundary-Layer Theory by H.Schlichting, 7th Edition, McGraw Hill Book co., New York, 1979.

STRUCTURAL ANALYSIS-I 

Text Books :
1. Elementary Structural Analysis by Norris, Wilbur and Utku, McGraw Hill.
2. Basic Structural Analysis by C.S. Reddy, Tata McGraw Hill.
3. Intermediate Structural Analysis by C.K.Wang, McGraw Hill
4. Theory of Structures – Volumes 1 and 2 by S. P. Gupta and G. S. Pandit, Tata McGraw Hill.
5. Structural Analysis by L.S.Negi & R.S.Jangid, Tata McGraw Hill.
6. Application of Graphics in Engg. by L.B.Roy, Standard Pub. and Dist., Delhi.
7. Structural Analysis Vol 1 by Bhavikatti Vikash Publishing House Pvt. Ltd
8. Structural analysis by R.C. Hibbler Pearson

[Engineers’ Forum Reviews: Structural analysis by Bhavikatti is a book for beginner and may be used for semester prep. but one may find a problem in reading the book as it lacks much in concepts.
*structural analysis by C.S. reddy  is a nice book but the problems are not written in stepwise one may face difficulties in analyzing the problem if you don't have in-depth understanding of basic concepts.
*Structural analysis by Hibbler is one of the best books for the subject within depth explanation of a basic concept, illustrative figures and stepwise analysis of problems you will never miss a concept]

·                  STRUCTURAL ANALYSIS –II 

(1) Matrix analysis of framed structures by W.Weaver and J.M.Gore, Van Nostrand.

(2) Basic Structural Analysis by C.S.Reddy, Tata McGraw Hill, New Delhi.

(3) Theory of Matrix Structural Analysis by J.S. Przemieniecki, Dover, New York.

(4) Structural Analysis – A Matrix Approach by G.S. Pandit and S.P. Gupta, Tata McGraw Hill, New Delhi

(5) Matrix Methods of Structural Analysis by M.B. Karchi, Wiley Eastern, New Delhi.

(6) Structural Analysis Vol II by Bhavikatti Vikash , Publishing House Pvt. Ltd

ENGINEERING HYDROLOGY 

Reference/Text Books :
1. Engineering Hydrology by K. Subramanya, Tata McGraw Hill Pub., New Delhi.
2. Applied Hydrology by V.T.Chow et. al., McGraw Hill International, New York.
3. Elementary Hydrology by V.P.Singh Prentice Hall.
4. Groundwater by H.M.Raghunath, Wiley Easter Ltd.
5. Groundwater Hydrology by D.K. Todd, John Wiley and sons.

CIVIL ENGINEERING DRAWING 

Text Books :
(1) Building Drawing by B.P. Verma, Khanna Pub., Delhi
(2) Engineering Drawing by N.D. Bhatt.

SOIL MECHANICS & ROCK MECHANICS 

Text Books :
1. A Text-Book of Soil Mechanics and Foundation Engineering, Revised and enlarged 4th Edition 1993 by V.N.S. Murthy, Saikripa Technical Consultants, Bangalore.
2. Basic and Applied Soil Mechanics by Gopal Ranjan and A.S.R.Rao, Wiley Eastern Ltd., New Delhi.
3. Soil Mechanics and Foundation Engineering by K.R.Arora, Standard Pub. and Dist., Delhi., 1992.
4. Introduction to Rock Mechanics by R.E. Goodman, John Wiley and Sons, New York.
5. Rock Mechanics and Engineering by Jacger, Charles, Cambridge University Press, London.
Reference Books :
(1) Soil Mechanics in Engineering Practice by Terzaghi and Peck, John Wiley and Sons Inc. New York, 1967
(2) Soil Mechanics by Lamb and Whitman, Wiley Eastern Pvt. Ltd., New Delhi, 1969.
(3) Fundamentals of Soil Mechanics by Taylor, John Wiley and Sons Inc New York, 1948.
(4) Tunnels: Planning, Design, Construction by Megaw, T.M. and J.V. Bartlett. International Edition, Ellis Horwood Limited, John Wiley and Sons, New York.

DESIGN OF CONCRETE STRUCTURE-I 

Text Books:
1. IS-456-2000 Code of the practice of plain and Reinforced concrete.
2. Design of Reinforced concerts structure by P.Dayaratnam, Oxford IBM publication, New Delhi
3. Reinforced concrete Design by S.N.Sinha, Tata McGraw Hill New Delhi

ENVIRONMENTAL ENGINEERING – I 

Text Books:
1. Environmental Engineering by Peavy H. S, Rowe D.R. and Techobanoglous G. Tata McGraw Hills, New Delhi.
2. Introduction to Environmental Engineering & Science 2nd Ed. by Gilbert M. Masters. Prentice-Hall. New Jersey.
3. Environmental engineering-i by Garg S.K., Khanna Publishers, New Delhi.
Reference Books:
1. Elements of Water Supply and Wastewater Disposal by G.M Fair. J.C.Geyer. D.A. Okan, John Wiley and Sons Inc.
2. Water Supply and Sewerage by Terence, J McGhee, McGraw Hill Book Co.
3. Water and Waste Water Technology by M.J. Hammer, John Wiley and Sons. New York
4. CPHEEO Manual on water supply and treatment, Ministry of Urban Development.
5. Environmental Management by GN Pandey, Publishing House Pvt. Ltd

ENVIRONMENTAL ENGINEERING-II 

Text Books :

1. Wastewater Engineering Treatment and Reuse by Metcalf & Eddy, TMH Publication.
2. environmental engineering -ii by Garg S.K., Khanna Publishers, New Delhi.

Reference Books :

1. Elements of water supply and waste-water Disposal by G.M.Fair. J.C.Geyer, D.A.Okan, John Wiley and Sons Inc.

2. Water supply and sewage by Terence, J. McGhee, McGraw Hill Book Co.

3. Water and Waste Water Technology by M.C.Hammer, John Wiley and Sons, New York.

4. CPHEEO: Manual on sewerage and Sewage Treatment, Ministry of Work and Housing, New Delhi.

TRANSPORTATION ENGINEERING – I

Text Books :
1. Highway Engineering by Khanna, S.K. and Justo, S.E.G., Nemchand Bros., Roorkee.
2. Principle and design of pavements by Kadiyali, L. R., Khanna Publishers, New Delhi
Reference Books:
1. Highway Engineering by Wright, P.H., John Wiley and Sons, New York
2. An Introduction to Transportation Engineering and planning by Morlok, E.R., McGraw Hill, Kagakusha international student Education.
3. Introduction to Transportation Engineering by Hay. W.W., John Wiley and sons, New York.
4. Fundamentals of Transportation Engineering by Papacostas, C. S., Prentice hall of India, New Delhi
5. Pavement Analysis and Design by Huang, Y. H., Prentice-Hall, Englewood Cliffs, New Jersey.
[Engineers’ Forum Reviews: Most recommended & widely used book is that by Khanna &Justo]

TRANSPORTATION ENGINEERING-II

1. An introduction to Transportation, Engineering and Planning by Morlok, E. R., McGraw Hill Kagakusha International Student Edition.

2. Traffic Engineering and Transportation Planning by Kadiyali, L. R., Khanna Publishers, New Delhi.

3. Introduction to Transportation Engineering by Hay, W. W., John Wiley and sons, New York.

4. Fundamentals of Transportation Engineering by Papacostas, C.S. Prentice Hall of India, New Delhi.

5. Principles of Urban transportation Planning by Hutchinson, B. G., McGraw Hill Book company.

6. A Text-Book of Railway Engineering by Saxena, S.C.Arora, S. P., Dhanpat Rai & Sons< New Delhi.

7. Railway Track Engineering by Munday, J. S., Tata McGraw Hill, New Delhi.

8. Indian Railway Track by Agarwal, M. M., Sachdeva press, Mayapuri, New Delhi.

9. Railroad Engineering by Hay, W .W. John Wiley and Sons, New York. Delhi

DESIGN OF STEEL STRUCTURES 

Text Books:
1. Design of steel Structure by A.S Arya and J.I. Ajmani, Nemchand Bros.
2. Design of steel Structure by S.M.A. Kazimi and R.S. Jindal, Prentice Hall (India) New Delhi
3. Design of Steel Structures by S.K.Duggal, Tata McGraw Hill, New Delhi.
4. Design of steel Structure by Negi, Tata McGraw Hills, New Delhi.

[Engineers’ Forum Reviews: steel structure by Negi can be considered as a handbook containing basic formulas & required codes
while that by Duggal is a more detailed treatise on the subject, & the newer reprint is based on the limit state design of steel structure]

FOUNDATION ENGINEERING 

Text Books:
1. A Textbook of Soil Mechanics and Foundation Engineering, Revised and enlarged 4th edition, 1993. by V.N.S. Murthy, Saikripa Technical Consultants, Bangalore.
2. Basic and Applied soil Mechanics by Gopal Ranjan and A.S.R.Rao, Wiley Eastern Ltd. New Delhi 1992.
Reference Books:
1. Foundation Engineering by R.B. Peck, W. E. Hanson and T. H. Thournburn, John Wiley, New York.
2. Foundation analysis Design by J.E. Bowles, McGraw Hill Book co. New York.
3. Foundation Engineering by G.A.Leonard, McGraw Hill Book co. New York.
4. Engineering Principle of Ground Modification by M.R.Hausmann, McGraw Hill International Edition, New York.

DESIGN OF HYDRAULIC STRUCTURES 

Text Books :
1. Fundamental of Irrigation Engineering by Bharat Singh, Nemchand Bros., Roorkee, Uttarakhand.
2. Irrigation & Water Power Engineering by Punima B.C., Pande Lal B.B., Laxmi Publication Pvt. Ltd. New Delhi.
3. Water Resource Engineering by Garg S.K., Khanna Publishers, New Delhi.
4. Water Power Engineering by Dandekar MM/ Sharma KN, Vikash Publishing Pvt. Ltd
Reference Books :
1. Water Resources Engineering by R.K. Linsley & J.L.H. Paulhus, McGraw Hill.
2. Hydroelectric Handbooks by W.P. Creager & J.D. Justin, John Wiley & Sons.

DESIGN OF CONCRETE STRUCTURES-II 

Text/ Reference Books:
1. Plain and Reinforced Concrete, Vol. I and II. by J. Krishna and O. P. Jain, Nemchand Bros. Roorkee.
2. IS 456, 2000. Code of Practice for Plain and Reinforced concrete.
3. Design Aids for R.C. to IS 456-2000.
4. Design of Reinforced Concrete Structures by P. Dayaratnam, Oxford- IBM Publishing Co., New Delhi.

CONSTRUCTION PLANNING AND MANAGEMENT 

Text Book:
1. Construction Planning and Management by U. K. Srivastav.

CONTRACT, SPECIFICATION AND ESTIMATION 

Text Books :
1. Estimating and Costing by B. N. Dutta, Tagore Palli, Lucknow.
2. Quantity surveying by, P. L. Basin, S. Chand and Company, Delhi.
3. Building Construction and Estimating by G. H. Cooper. McGraw-Hill.
4. Construction Project Scheduling and Control, 2nd Edition by Saleh Mubarak, Wiley

FINITE ELEMENT METHODS 

Text Books:
1. The Finite Element Method by O. C. Zienkiewiez, Tata McGraw Hill.
2. Numerical Methods in Finite Element Method Analysis by Wilson, E. L. And Bathe, K. J., Prentice-Hall Englewood Cliffs.

WATER AND LAND MANAGEMENT 

Text Books:

1. Irrigation Theory and Practice by A. M. Michael, Vikas, Pub., New Delhi.

2. FAO Irrigation and Drainage Paper no. 24 & 58, Rome, Italy.

3. Irrigation Engineering by G. L. Aswa, Wiley Eastern, New Delhi.

4. Irrigation Engineering by S. K. Mazumdar, Tata McGraw Hill Pub., New Delhi.

Reference Books :

1. Diagnostic Analysis of Minor irrigation scheme, Publication no. 11, WALMI, Aurangabad (Maharashtra).

2. Application of soil survey in Irrigation Water Management, Publication no. 21, WALMI, Aurangabad (Maharastra).

3. Irrigation: Gravity Methods and Efficiencies, Publication no. 15. WALMI, Aurangabad (Maharashtra).

AIR POLLUTION ENGINEERING 

Reference Books:

1. Air Pollution by Rao & Rao, TMH.

2. Air Pollution Control Engineering by Rao, TMH.

RIVER HYDRAULICS AND SEDIMENT TRANSPORT 

Text Books:
1. Mechanics of Sediment Transport and Alluvium Stream Problems by R. J. Grade and K. G. Rangaraju, Wiley
Eastern Ltd., New Delhi.
2. Manual of River Behaviors, Control and Training by D. V. Joglekar, CBIP, Pub., No. 60, 1971.
3. Irrigation Engg. by G. L. Aswa, New Agro Int. (P) Ltd. Pub., New Delhi.
4. River Engg. by M.S. Peterson, PHI, New Delhi

STRUCTURAL DYNAMICS 

Text Book :
1.Dynamics of Structures by Patrick Paultre, Wiley
2. Dynamics of Structures by Clough & Penzien , MC- Graw- Hill

TRANSPORTATION SYSTEMS AND PLANNING 

Text Books :
1. Regional Development Planning in India by Prakash Rao and Sundaram, Vikas Publishing House.
2. Urban Transportation Systems Planning by B.G.Hutchinson, Introduction to McGraw Hill.
3. Urban Public Transportation Systems and Technology by Vukan R. Vuchin, Prentice Hall Inc., N.J.
4. Public Transportation Planning Operations and Management by G.E. Gray and L.A. Hoel, Prentice Hall Inc.

WATER RESOURCES PLANNING AND MANAGEMENT 

Text Books :
1. Water Resources Engineering by R.K.Linsley and J.B.Franzini, McGraw Hill Book Co., New York.
2. Water Resources System Planning & Economics by R.S. Varshney, Nem Chand, Bros. Roorkee.
3. Water Resources Systems Engg. by W.A. Hall and J.C. Dracup, McGraw Hill Book Co., New York.
4. Water Resources Engineering by Larry W. Mays, Wiley

SOIL DYNAMICS 

Text Book :
1. Handbook of Machine Foundations by Srinivasulu and Vaidyanathan, TMH, New Delhi.

ADVANCED FOUNDATION ENGINEERING 

Text Books:
1. Analytical and computer method in the foundation by J.E.Bowels, McGraw Hill Books Co., New York.
2. Numerical Methods in Geotechnical Engineering by C.S. Desai and J.T. Cristian, McGraw-Hill Book Co., New York.

WATER POWER ENGINEERING 

Text Books :
1. Water Power Engg. by M.M Dandekar and K.N. Sharma, Vikas Publishing house, New Delhi.
2. Hydropower Structures by R.S.Varshney, Nem Chand and Bros., Roorkee.

BRIDGE ENGINEERING 

Reference/Text Books:
1. Bridge Engineering by Vector et. al., TMH.
SYSTEMS ENGINEERING

ENVIRONMENTAL IMPACT ASSESSMENT 

Textbooks :
1. Environmental Impact Assessment by Canter, McGraw Hill Inc.,

IRRIGATION ENGINEERING 

Text Books :
1. Fundamental of Irrigation Engineering by Bharat Singh, Nemchand Bros., Roorkee, Uttarakhand.
2. Irrigation & Water Power Engineering by Punima B.C., Pande Lal B.B., Laxmi Publication Pvt. Ltd. New Delhi.
3. Water Resource Engineering by Garg S.K., Khanna Publishers, New Delhi.
4. Irrigation Theory & Practice by Micheal A.M., Vikas Publication, New Delhi.
Reference Book :
1. Water Resources Engineering by R.K. Linsley & J.L.H. Paulhus, McGraw Hill.

LAND DRAINAGE 

Text Books :
1. Fundamental of Irrigation Engineering by Bharat Singh, Nemchand Bros., Roorkee, Uttarakhand.
2. Irrigation & Water Power Engineering by Punima B.C., Pande Lal B.B., Laxmi Publication Pvt. Ltd. New
Delhi.
3. Water Resource Engineering by Garg S.K., Khanna Publishers, New Delhi.
4. Irrigation Theory & Practice by Micheal A.M., Vikas Publication, New Delhi.
Reference Book :
1. Water Resources Engineering by R.K. Linsley & J.L.H. Paulhus, McGraw Hill.

FLOODS AND DROUGHTS 

Text Books :
1. Engineering Hydrology by Muteraja.
2. Engineering Hydrology by Subramaniam
3. Watershed Hydrology by R. Suresh, Standard.

GROUNDWATER ENGINEERING 

Text Books :
1. Groundwater Hydrology by M. H. Raghunath, New Age Publication, New Delhi.
2. Irrigation Engineering and Hydraulic Structures by Sahasrabuddhe. S. R., Katson, Ludhiana, 1975.
Reference Book :
1. 'Ground Water Hydrology' by Todd, David Keith (2007), Wiley India Edition, New Delhi

 ADVANCED SOIL MECHANICS 

Text Book :
1. Soil Mechanics, Lambe T. W. And Whitman, R. V. (1979), John Wiley & Sons Inc.
2. Soil Mechanics and Foundation Engineering, V. N. S. Murthy, Sai Kripa Publication, Bangalore.
3. Geotechnical Engineering, S. K. Gulathy et. al., TMH Publication, New Delhi.