oettl, barbara oiticica, helio * oldenburg, claes * (2) olschki, leonardo omahony, marie onians, john *   onstad kunstsenter henie- -> henie-onstad kunstsenter oppen, v oppenberg, ferdinand oppenheim, meret * oppenheimer, max * ordonez, eugena orlan * orland, barbara ortenau, erich ortmeier, martin ortwed, kirsten * os, henk van