Spectral classification of O–M stars on the basis of UBV photometry V. I. Kuznetsov, G. Z. Boutenko, G. A. Lazorenko and P. F. Lazorenko Astron. Astrophys. Suppl. Ser., 142 3 (2000) 389-398 Published online: 15 March 2000 DOI: 10.1051/aas:2000159