1. Alexandrova, G. J.: Pecularities of haemagglutination inhibition test with type A2 influenza viruses. Acta virol.4, 1 (1960).
2. —: An analysis of the structure of populations of inhibitor sensitive and inhibitor resistent A2 influenza virus strains. Acta virol.6, 487 (1962).
3. Antoniadis, G. J.: Photometrische Bestimmung der Konzentration von Erythrozytensuspensionen. Zbl. Bakt., I. Abt. Orig.188, 267 (1963).
4. Burnet, F. M., andP. E. Lind: Recombination of influenza viruses in the deembryonated egg. I. The use of periodate-treated sera for in vitro characterization of influenza virus strains. Aust. J. exp. Biol. med. Sci.32, 146 (1954).
5. Choppin, P. W., andI. Tamm: Two kinds of particles with contrasting properties in Influenza A virus strains from the 1957 pandemic Virology8, 539 (1959).