@article{MS2_1970__27_166146,
     author = {Donald Monk},
     title = {On {Equational} {Classes} of {Algebraic} {Versions} of {Logic} {I.}},
     journal = {Mathematica Scandinavica},
     pages = {53--71},
     publisher = {mathdoc},
     volume = {27},
     year = {1970},
     zbl = {0208.01202},
     url = {http://geodesic.mathdoc.fr/item/MS2_1970__27_166146/}
}