Back crossing : the theory and practice of the backcross method in the breeding of some non-cereal crops / by Mary Thomas. Thomas, Mary. Plant breeding. 631.523 18 Includes bibliographical references and index. Cambridge : Commonwealth Bureau of Plant Breeding and Genetics, 1952. 1952. 1952 Text vi, 136 p. : eng Commonwealth Bureau of Plant Breeding and Genetics, Cambridge, Eng. Technical communication 16