The deepest tradition in ISM study in the optical range was built in Russia/FSU by V.Fessenkov, the founder of Fessenkov Astrophysical (Aph) Institute (AFIF, Kazakhstan) and G.Shain (Crimean Aph.Obs. - CrAO, Ukraine). The tradition was handed over to SAI (Moscow) by I. Shklovski and S.Pikelner, to Abastumani Aph. Obs. (AAO, Georgia), where a catalogue of dark nebulae (Khavtassi, 1960) was produced, and to Byurakan Aph. Obs. (BAO, Armenia).
For a long time 0.3-0.7 m telescopes were used for determination of interstellar extinction in the Galaxy by the standard technique (SAI; Engelhart Astron. Obs. of Kazan Univ., Russia; AAO; BAO and others. The most sophisticated investigations were carried out in Lithuania (e.g. Straizys, 1977; Sudzius, 1974).