1. Anderson OA: Zur Kenntnis der Morphologie der Schilddrüse. (Studies on the morphology of the thyroid gland). Arc. Anat. Entw. Anat. Abth. 1984, 117, 225–268.
2. Anon.: A survey of the incidence and causes of mortality in pigs. I. Sow survey. Vet. Rec. 1959, 71, 777–786.
3. Aron M: Indications apportées par la methode des injections hypophysaires sur le fonctionnement de la thyroide et ses tests morphologiques. (Studies on the function and morphology of the thyroid gland using injections with extracts from the hypophysis). Compte rende Soc. Biol. 1930, 103, 148–150.
4. Bengtsson A-C, Svendsen J, Persson G: Jämförande undersökning av dräktiga suggor i 4 olika inhysningssystem: Beteendestudier och renhetsstudier. (Comparison of four types of housing for sows in gestation: Behaviour studies and hygiene studies). Report 36. Dept. Farm Buildings, Swedish Univ. Agric. Sci. Lund 1983.
5. Bille N, Nielsen NC, Larsen JL, Svendsen J: Preweaning mortality in pigs. II. The perinatal period. Nord. Vet.-Med. 1974, 26, 294–313.