- [Walhund effect](http://www.uwyo.edu/dbmcd/molmark/lect05/lect5.html) - [Eshel & Cavalli-Sforza, 1982](http://doi.org/10.1073/pnas.79.4.1331) - [Peck & Feldman, 1986](http://doi.org/10.1086/284479) - [Hammond & Axelrod, 2006](http://doi.org/10.1177/0022002706293470)
