De Melo, C. A M [UNESP]Pimentel, B. M. [UNESP]Pompeia, P. J. [UNESP]2014-05-272014-05-272006-02-01Nuovo Cimento della Societa Italiana di Fisica B, v. 121, n. 2, p. 193-200, 2006.1594-9982http://hdl.handle.net/11449/68771A manifestly covariant treatment of the free quantum eletromagnetic field, in a linear covariant gauge, is implemented employing Schwinger's variational principle and the B-field formalism. It is also discussed the Abelian Proca model as an example of a system without constraints. © Società Italiana di Fisica.193-200engArtigo10.1393/ncb/i2006-10014-1WOS:000238402200009Acesso restrito2-s2.0-33745651371