@article{SF_1976__13_134227,
     author = {A. Stralka},
     title = {Congruence extension and amalgamation in {C{\textsterling}.}},
     journal = {Semigroup forum},
     pages = {355--376},
     publisher = {mathdoc},
     volume = {13},
     year = {1976},
     zbl = {0354.06003},
     url = {http://geodesic.mathdoc.fr/item/SF_1976__13_134227/}
}