1. N. E. Steenrod, ?Cohomology invariants of mappings,? Ann. Math.,50, No. 2, 954?988 (1949).
2. F. P. Peterson, ?Functional cohomology operations,? Trans. Am. Math. Soc.,86, 187?197 (1957).
3. E. Brown, ?Twisted tensor products,? Mathematics,6, No. 1, 33?59 (1962).
4. N. A. Berikashvili, Differentials of Spectral Sequences [in Russian], Tr. Tbil. Mat. Inst. im A. M. Razmadze, Tbilisi (1976), T. LI.
5. V. A. Smirnov, ?Functor D and strong homotopy,? Mat. Zametki,24, No. 4, 557?564 (1977).