1. The Anatomy and Physiology of Capillaries;Krogh,1929
2. On differences in the vascular colouration of various regions of the normal human skin;Wetzel;Heart,1927
3. Die Verteilung der Blutgefasse in der Haut;Spalteholz;Arch. f. Anat. u. Physiolog., Leipz,1893
4. Ueber unmittelbare Einmundung kleinster Arterien in Gefass-aste venôsen Charakters;Hoyer;Arch. f. Mikro. Anat,1877
5. Observations on direct communications between arteries and veins in the rabbit's ear;Grant;Heart,1930