Ichthyofauna in small lakes of the Paanajärvi National ParkShustov, Yuri.; Sõstra, Ülo; Kuusela, Kalevi; Pervozvansky, Vladimir; Shirokov, Vyacheslav; Koutaniemi, LeoOulanka reports2000 / p. 121-125 : ill

Springs along the Astervajärvi nature path in Paanajärvi National ParkBrodulina, Galina; Sõstra, ÜloOulanka reports2001 / p. 5-8

The Kivakka Layered IntrusionAlapieti, Tuomo; Sõstra, Ülo; Asnakew, HabteOulanka reports2000 / p. 25-30 : ill