1. P. Margaretha,Angew. Chem. 84, 308 (1972).
2. I. é. Lielbriedis and G. Ya. Dubur, in: The Chemistry of Dicarbonyl Compounds, Reports of the 5th All-Union Conf., Riga (1981), p. 131.
3. M. F. Strozhev, Ya. A. Miller, and I. é. Lielbriedis, in: The Chemistry of Dicarbonyl Compounds, Reports of the 5th All-Union Conf., Riga (1981), p. 182.
4. Determination of the Structures of Organic Compounds by Physical and Chemical Methods, Vol. 1 [in Russian], Khimiya, Moscow (1967), p. 532.
5. O. Ya. Neiland,Izv. Akad. Nauk Latv. SSR, Ser. Khim., No. 5, 577 (1964).