@article{MS2_1974__34_166354,
     author = {Hans Engenes},
     title = {Subobject {Classifiers} and {Classes} of {Subfunctors.}},
     journal = {Mathematica Scandinavica},
     pages = {145--152},
     publisher = {mathdoc},
     volume = {34},
     year = {1974},
     zbl = {0291.18002},
     url = {http://geodesic.mathdoc.fr/item/MS2_1974__34_166354/}
}