Barton, N. H. (1983). Multilocus clines. Evolution; International Journal of Organic Evolution. Society for the Study of Evolution.https://doi.org/10.2307/2408260 

Barton, N. H. (1982). The structure of the hybrid zone in Uroderma bilobatum (Chiroptera: Phyllostomatidae). Evolution. Wiley.https://doi.org/10.1111/j.1558-5646.1982.tb05452.x 

Barton, N. H., &; Hewitt, G. (1981). A chromosomal cline in the grasshopper Podisma pedestris. Evolution; International Journal of Organic Evolution. Wiley-Blackwell.https://doi.org/ 10.1111/j.1558-5646.1981.tb04966.x