1. AFONINA, O.M., BREDKINA, L.I., MAKAROVA, I.I.: Bot. Zh. Leningrad 65, 66–82 (1980).
2. — AHMADJIAN, V.: Separation and artificial synthesis of lichens, 3–29. In: Cellular Interactions in Symbiosis and Parasitism, eds. C.B. COOK, P.W. PAPPAS, E.D. RUDOLPH. Columbus: Ohio State Univ. Press 1980.
3. — AHMADJIAN, V., RUSSEL, L.A., HILDRETH, K.C.: Mycologia 72, 73–89 (1980).
4. — AHTI, T.: Ann. Bot. Fennici 17, 195–243 (1980a).
5. — AHTI, T.: Lichenologist 12, 125–133 (1980b).