1. Andresen , E. 1963 A study of blood groups of the pig 39 44
2. Na- und Nb-Antigen-Substanzen im Serum des Schweines;Brucks;Blut,1969
3. The blood groups of the pig. The A antigen-antibody system and haemolytic disease in newborn piglets;Goodwin;J. comp. Path.,1956