By Mahajan

Published by S.Chand and Co., 1962

By Richard Johnson and Gouri Bhattacharyya

Published by John Wiley and sons, 1987

By Allen L. Edwards

Published by National Book Foundation, 1986

By Kerson Huang

Published by Wiley eastern Ltd., 1988

By Bipin K Agarwal, Melvin Eisner

Published by Wiley Eastern Ltd, 1989

By Thomas P.Ryan

Published by John Wiley and sons, 1989

By Reif F

Published by McGraw Hill

Published by Bearu of Statistics Government of the punjab, 1985

Published by Bearu of Statistics Government of the punjab, 1985

By A. Hald

Published by National Book Foundation, 1980