1. Zur Superfetation beim Pferd [On superfetation in horses];Arbeiter K.;Deutsche Tierarztiche Wochenschrift,1965
2. A case of superfoetation in the cow;Gee C. D.;Australian Veterinary Journal,1971
3. Short communication: Bovine superfetation by natural conception secondary to an embryo transfer pregnancy;Hall W. H.;Cornell Veterinarian,1987
4. Retention of dead fetuses in utero and its bearing on the problems of superfetation and superfecundation