By D.R. Dasgupta & P.K.Koshy

Published by Anmol Publications, 1989

By Johansen Dopnald Alexander

Published by Mc Graw Hill, 1968

By A. Johnston and C. Booth (Editors)

Published by Oxford and IBH Publishing Co., 1983

By Walker John Charles

Published by Mc Graw Hill, 1969

By John Charles Walker

Published by Mcgraw Hill International book, 0

By Meyer S.Bernard and Donald B Anderson

Published by Maruzen Co., 0

By Salisbury and Ross

Published by National Book Foundation, 2004

By Hudront Hartmann and Dale E. Kester

Published by Prentice Hall of India Private Ltd., 1989

By R.F.Daubenmire

Published by National Book Foundation, 1984

By C.J.Bamber, M.V.O

Published by Supperintendent Govt. Printing Punjab, 1916