Keeton, William T. 1980. Biological science. New York: Norton. ISBN0-393-95021-2, p. 800
Rong, R.; Chandley, A. C.; Song, J.; McBeath, S.; Tan, P. P.; Bai, Q.; Speed, R. M. (1988). "A fertile mule and hinny in China". Cytogenetics and cell genetics. 47 (3): 134–9. PMID3378453.doi:10.1159/000132531
Baker, H. G. (1959). "Reproductive methods as factors in speciation in flowering plants". Cold Spring Harb Symp quant Biol. 24: 177–191.PMID13796002. doi:10.1101/sqb.1959.024.01.019.
Barton N.; Bengtsson B. O. (1986), "The barrier to genetic exchange between hybridising populations", Heredity, 57 (3): 357–376,PMID3804765, doi:10.1038/hdy.1986.135
Strickberger, M. 1978. Genética. Omega, Barcelona, España, p.: 874–879. ISBN84-282-0369-5.
Futuyma, D. 1998. Evolutionary biology (3ª edición). Sinauer, Sunderland.
Barton N.; Bengtsson B. O. (1986), “The barrier to genetic exchange between hybridising populations”, Heredity 57 (3): 357–376, PMID3804765, doi:10.1038/hdy.1986.135 Đã bỏ qua tham số không rõ |doi-access= (trợ giúp)
Barton N.; Hewitt G. M. (1985), “Analysis of hybrid zones”, Annual Review of Ecology and Systematics 16 (1): 113–148, doi:10.1146/annurev.es.16.110185.000553
Baker H G (1959), “Reproductive methods as factors in speciation in flowering plants”, Cold Spring Harb Symp Quant Biol 24: 177–191, PMID13796002, doi:10.1101/sqb.1959.024.01.019
Grant V (1966), “The selective origin of incompatibility barriers in the plant genus Gilia”, Am Nat 100 (911): 99–118, doi:10.1086/282404
Grant K, Grant V (1964), “Mechanical isolation of Salvia apiana and Salvia mellifera (Labiatae)”, Evolution 18 (2): 196–212, JSTOR2406392, doi:10.2307/2406392
Jain SK, Bradshaw AD (1966), “Evolutionary divergence among adjacent plant populations. I. The evidence and its theoretical analysis”, Heredity 21 (3): 407–441, doi:10.1038/hdy.1966.42 Đã bỏ qua tham số không rõ |doi-access= (trợ giúp)
Mayr, E (1963), Animal species and evolution, Harvard University Press
McNeilly T (1967), “Evolution in closely adjacent plant populations. III. Agrostis tenuis on a small copper mine”, Heredity 23 (1): 99–108, doi:10.1038/hdy.1968.8 Đã bỏ qua tham số không rõ |doi-access= (trợ giúp)
