@article{10_4064_fm_47_1_57_103,
     author = {S. Feferman and R. Vaught},
     title = {The first order properties of products of algebraic systems},
     journal = {Fundamenta Mathematicae},
     pages = {57--103},
     publisher = {mathdoc},
     volume = {47},
     number = {1},
     year = {1959},
     doi = {10.4064/fm-47-1-57-103},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-47-1-57-103/}
}