N. H. Barton, “Multilocus clines,” Evolution; International Journal of Organic Evolution, vol. 37, no. 3. Society for the Study of Evolution, pp. 454–471, 1983.

N. H. Barton, “The structure of the hybrid zone in Uroderma bilobatum (Chiroptera: Phyllostomatidae),” Evolution, vol. 36, no. 4. Wiley, pp. 863–866, 1982.

N. H. Barton and G. Hewitt, “A chromosomal cline in the grasshopper Podisma pedestris,” Evolution; International Journal of Organic Evolution, vol. 35, no. 5. Wiley-Blackwell, pp. 1008–1018, 1981.