[Dawson, J. W. (1993). "The compactness of first-order logic:from gödel to lindström". History and Philosophy of Logic. 14: 15. doi:10.1080/01445349308837208.]
springer.com
link.springer.com
Dirk van Dalen, (1980; Fifth revision 2013) "Logic and Structure" Springer. (See page 1.)