1. A. Almenninger, O. Bastiansen, L. Fernholt, et al., ?Structure and barrier of internal rotation of biphenyl derivatives in the gaseous state,? J. Mol. Struct., 128, No. 1, 59?76 (1985).
2. O. Bastiansen and S. Samdal, ?Structure and barrier of internal rotation of biphenyl derivatives in the gaseous state. 4,? ibid., 128, No. 1, 115?125 (1985).
3. L. G. Chilikin, ?Synthesis and investigation in the 3,5-bis-1H-indole series,? Author's Abstract of Dissertation for the Degree of Candidate of Chemical Sciences, Moscow (1979).
4. P. P. Zarin', É. S. Lavrinovich, and A. K. Aren, ?Pyridinium salts,? Khim. Geterotsikl. Soedin., No. 1, 104?114 (1974).
5. I. I. Grandberg, S. B. Nikitina, A. N. Kost, and G. K. Faizova, ?Conjugation of aromatic heterocycles,? Izv. Timiryazev. S.kh. Akad., No. 6, 219?221 (1968).