Hopkins; Rall
Preprints - American Chemical Society, Division of Petroleum Chemistry, 1957 , vol. 2, # 1 p. 231,233, 237
Chem.Abstr., 1960 , p. 24 704

Phillips,B.A. et al.
Tetrahedron, 1973 , vol. 29, p. 3309 - 3327

v. Braun; Schmitz
Chemische Berichte, 1906 , vol. 39, p. 4366