Milk from cows of different β-casein genotypes as a source of β-casomorphin-7.
G. Ceriotti, D. Cieślińska A, Kostyra E, Kostyra H, Oleński K, Fiedorowicz E, Kamiński S. Int J Food Sci Nutr. 2012 Jun;63(4):426-30. doi: 10.3109/09637486.2011.634785.

Associations between β-casein genotype and milk yield and composition in grazing dairy cows
Morris CA, Hickey SM, Cullen NG, Prosser CG, Anderson RM, Tate ML. 2005. New Zealand Journal of Agricultural Research 48:441–450.

Milk protein loci polymorphism in taurine (Bos taurus) and zebu (Bos indicus) populations bred in hot climate.
G. Ceriotti, D. Marletta, A. Caroli, G. Erhardt. (2004). Journal of Animal Breeding and Genetics 121 (6), 404– 415.

Genetic Polymorphism of Milk Proteins (Chapter 16).
Ng-Kwai-Hang, K.F., and F. Grosclaude. (2002). Chapter 16 pp 737-814 In Advanced Dairy Chemistry: Volume 1 – Proteins, 2nd Edition (edited by P.F. Fox and P. L. H. McSweeney). Kluwer Academic/Plenum Publishers, New York

Casein polymorphism and relation between milk production traits.
G. Freyer, Z. Liu, G. Erhardt, L. Panicke. (1999). Journal of Animal Breeding and Genetics 116 (2), 87–97.

Milk protein polymorphism: detection and diffusion of the genetic variants in Bos genus.
P. Formaggioni, A. Summer, M. Malacarne, P. (1999). Mariani Università degli Studi di Parma, Annali della Facoltà di Medicina Veterinaria Vol. XIX

Association between milk protein genetic variants and genetic values of Canadian Holstein bulls for milk yield traits.
Sabour MP, Lin CY, Lee AJ, McAllister AJ..J Dairy Sci. 1996 Jun;79(6):1050-6.

Milk Protein Polymorphisms in California Dairy Cattle.
Alison van Eenennaam and Juan Fernando Medrano. (1991). J Dairy Sci 74:1730-17

Beta casein & variant genetics