1. JONES and RUSSELL. Seventh Int. Congress of Phot. Proc, p.130, 1928.
2. EGGERT and ARENS, Seventh Int. Congress of Phot. Proc, p.128, 1928.
3. On the Relation Between Time and Intensity in Photographic Exposure*
4. RENWICK, Seventh Int. Congress of Phot. Proc, p.129, 1928.