Joonestamine üldhariduskoolileKogermann, Edgar; Tapper, Valentin; Tihase, Karl1985 https://www.ester.ee/record=b1256780*est

Joonestamine üldhariduskoolileKogermann, Edgar; Tapper, Valentin; Tihase, Karl1990 https://www.ester.ee/record=b1163664*est