Development and differentiation of vertebrate lymphocytes : proceedings of the Symposium on Development and Differentiation of Vertebrate Lymphocytes organized by the British Society for Developmental Biology held in Durham, United Kingdom, 6-7 September, 1979 - Horton, John D. (Elsevier/North-Holland Biomedical Press; sole distributors for the USA and Canada, Elsevier North Holland Inc., 1980)