@article{MOMA_1968__72_177433,
     author = {Alfred L. Foster},
     title = {Pre-fields and {Universal} {Algebraic} {Extensions;} {Equational} {Precessions.}},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {315--324},
     publisher = {mathdoc},
     volume = {72},
     year = {1968},
     zbl = {0162.32503},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1968__72_177433/}
}