1. Dräktighetsperiodens längd hos nötkreaturen inom Malmöhus län;Axelsson;Nord. Jordbr. forskn.,1929
2. Factors associated with the duration of gestations in dairy cattle;Brakel;J. Dairy Sci.,1952
3. Do the spermatozoa influence the duration of pregnancy in cattle;Düring;Z. f. Tierz. u. Zücht.-Biol.,1937
4. Abnormt lång dräktighet hos ko (graviditas prolongata cum sine partu serotina);Hallgren;Nord. Vet.-Med.,1951
5. Environmental sources of variation in the gestation length of the horse;Howell;J. Anim. Sci.,1951