Three reasons why it is likely that the early Mesolithic population in Poland was not aboriginal - Schild, Romuald 1938- (Problemy epoki kamienia na obszarze Starego Świata. Księga Jubileuszowa dedykowana Profesorowi Januszowi K. Kozłowskiemu. Problems of the Stone Age in the Old World. Jubilee Book dedicated to Professor Janusz K. Kozłowski., 2001)