March 2004 - Volume 110 Issue 3 Wild Chimpanzees Produce Group-Specific Calls: a Case for Vocal Learning? Catherine Crockford, Ilka Herbinger, Linda Vigilant, Christophe Boesch pp. 221 - 244
April 2004 - Volume 110 Issue 4 Vocal Repertoire of Sooty Mangabeys (Cercocebus torquatus atys) in the Ta� National Park Friederike Range, Julia Fischer pp. 301 - 322
