1. Stock, A., and C. Massenez, Ber., 1912, 45, 3529
2. Stock, A., and K. Friederici, Ber., 1913, 46, 1959
3. Stock, A., K. Friederici, and O. Priess, ibid.,p. 3353.
4. Dilthey, W., Z. angew. Chem, 1921, 34, 596.
5. Mark, H., and E. Pohland, Z. Krist., 1925, 62, 103.