An addition to “logic of many-sorted theories”
Compositio Mathematica, Tome 13 (1956-1958), p. 277-281
@article{CM_1956-1958__13__277_0,
     author = {Gilmore, P. C.},
     title = {An addition to ``logic of many-sorted theories''},
     journal = {Compositio Mathematica},
     publisher = {Kraus Reprint},
     volume = {13},
     year = {1956-1958},
     pages = {277-281},
     zbl = {0149.24502},
     mrnumber = {106176},
     language = {en},
     url = {http://www.numdam.org/item/CM_1956-1958__13__277_0}
}
Gilmore, P. C. An addition to “logic of many-sorted theories”. Compositio Mathematica, Tome 13 (1956-1958) pp. 277-281. http://www.numdam.org/item/CM_1956-1958__13__277_0/

Hao Wang, [1] Logic of many-sorted theories, the Journal of Symbolic Logic, vol. 17 (1952), pp. 105-116. | Zbl 0049.14802

Arnold Schmidt, [2] Die Zulässigkeit der Behandlung mehrsortiger Theorien mittels der üblichen einsortigen Prädikatenlogik, Mathematische Annalen, Vol. 123 (1951), pp. 187-200. | Zbl 0042.00605