1. S. MIALMASSON, R. AKESSON, Modern Kjeldahl Procedure, International Laboratory (Analytical Techniques), April 1983, p. 70.
2. Digital Nitrogen Detector, Model 720 (Antek), Unimat (Mess-und-Industrieanlagen GmbH, CoKG, Düsseldorf, FRG).
3. E. G. NIEMANN, Atomic Energy Review, 18 (1980) 125 (see also the references therein).
4. G. N. FLEROV, A. G. BELOV, W. E. ZHUCHKO, Yu. S. ZAMYATNIN, Report 18-83-699 JINR, Dubna 1983, (in Russian).
5. S. MUSZYŃSKI, Department of Plant Breeding and Seed Science, Warsaw Agriculture University, Warsaw, personal communication.