1. Casida jr., L. E.: Industrial Microbiology. John Wiley & Sons, Inc. New York 1964, 125.
2. Feud, Z.: Production of microbial protein from carbon sources. 2nd Int. Conf. Global Impacts Appl. Microbiol., Addis Ababa 1969. Proc. 63–70.
3. Frijs, J. & P. Ottolenghi: Localisation of invertase in a strain of yeast. G. R. Lab. Carlsberg. 1959, 31, 259–272.
4. Frommer, W. & E. Rauenbusch: Gewinnung von Hefen mit einem hohen Invertasegehalt. (Selection of yeasts with a high content of invertase). 2. Symp. Technische Mikrobiologie, Berlin 1970. Proc. 99–107.
5. Hildrum, K. I. & B. Næss: Gel filtration of lignosulphonic acids and peptide-precipitating abilities of the separated fractions. Acta vet. scand. 1972, 13, 293–304.