1. Yant, Schrenk, Sayers, Horvath andReinhart: J. ind. Hyg.18, 96 (1936).
2. Yant, Schrenk andPatty: J. ind. Hyg.18, 349 (1936).
3. Kammer, Isenberg andBerg: J. amer. med. Assoc.111, 1452 (1938).
4. Bowditch andElkins: J. ind. Hyg.21, 321 (1936).
5. Jephcott andBulmer: J. ind. Hyg.21, 321 (1939).