1. Washington (State) Univ. Puget Sound;ANGST E. G.;Biol. Sta. Pub.,1929
2. Cent. Bakt;ORIKURA J.;II Abt.,1928
3. Association of Official Agricultural Chemists. 1925 Methods of Analysis 2nd edition.
4. K;BEIJERINCK W. M.;Akad. Wetensch. Amsterdam. Verslag, 19, part,1911
5. Cent. Bakt;BIERNACKI W.;II Abt.,1911