1. C. A. Buehler and D. E. Pearson, Survey of Organic Syntheses, Interscience, New York (1970).
2. Organic Chemistry Laboratory Textbook [Russian translation], Mir, Moscow (1979), p. 150.
3. Weygand-Hilgetag, Experimental Methods in Organic Chemistry [Russian translation], Khimiya, Moscow (1969), p. 805
4. S. I. Zav'yalov, O. V. Dorofeeva, and O. K. Taganova, Izv. Akad. Nauk SSSR, Ser. Khim., 495 (1975).
5. E. Knoevenagel and R. Wenner, Liebigs Ann. Chem.,281, 80 (1894).