Photopolarimetric monitoring of OJ 287 in 1994–1997 Yu. S. Efimov, N. M. Shakhovskoy, L. O. Takalo and A. Sillanpää A&A, 381 2 (2002) 408-419 Published online: 15 January 2002 DOI: 10.1051/0004-6361:20011515