1. 4) E. M. Smolin, L. Rapoport, “s-Triazines and derivative” Interscience Publishers (1959)
2. 5) Elderfield, “Heterocyclic compounds” vol. 7 (1961)
3. 7) H. R. Allcock, “Heteroatom Ring Systems and Polymers”, Academic Press (1967)
4. 9) J. K. Simons, Org, Syntheses, 33, 13 (1953)
5. 11) BP 642,409 ; Chem. Abst., 46,146 (1952)