Buchan, J. (1921) The Path of the King. Thomas Nelson & Sons Ltd., London and Edinburgh.

Cooper, C. (2004) Twins and Multiple Births. Vermilion, London.

Crow, J.F. and Kimura, M. (1970) An Introduction to Population Genetics Theory. Harper and Row, New York.

Dawkins, R. (1976) The Selfish Gene. Oxford University Press.

Dawkins, R (1998) Unweaving the Rainbow. Allen Lane, London.

Elmhirst, P. (2004) Wills and Probate. Consumers' Association, London.

Falconer, D.S. (1989) Introduction to Quantitative Genetics. (3rd ed.). Longmans, Harlow, England.

Gilbert, M. (2005) Churchill and America. The Free Press, London.

Jones, S. (1996) In the Blood. Harper Collins, London.

Lasley, J.F. (1978) Genetics of Livestock Improvement. (3rd ed.). Prentice-Hall, Englewood Cliffs, New Jersey.

Warwick, E. J. and Legates, J.A. (1979) Breeding and Improvement of Farm Animals (7th ed.). Tata McGraw-Hill Publ. Co. Ltd., New Delhi.