  The formulae of the relativistic products are found S=1
Barut-Muzinich-Williams matrices. They are analogs of the well-known
Chisholm-Caianiello-Fubini identities. The obtained results can be useful in
the higher-order calculations of the high-energy processes with S=1 particles
in the framework of the 2(2S+1) Weinberg formalism, which recently attracted
attention again. PACS numbers: 02.90.+p, 11.90.+t, 12.20.Ds
