1. Ackermann, W. W., andS. Dinka: Concerning the nature of the viral neutralizing activity of bovine serum. Acta virol.9, 526?533 (1965).
2. Clarke, D. H., andJ. Casals: Techniques for hemagglutination and hemagglutination-inhibition with arthropod borne viruses. Amer. J. trop. Med. Hyg.7, 561?573 (1958).
3. Cohen, A., F. Biddle, andS. E. Newland: Analysis of horse serum inhibitors of A2 influenza virus hemagglutination. Brit. J. exp. Path.46, 497?513 (1965).
4. Cunnningham, C. H.: Newcastle disease and infectious bronchitis neutralizing antibody indexes of normal chickens serum. Amer. J. vet. Res.12, 129?133 (1951).
5. Doggett, J. E., D. Taylor-Robinson, andR. G. C. Gallop: A study of an inhibitor in bovine serum active against respiratory syncytial virus. Arch. ges. Virusforsch.23, 126?137 (1968).