@article{MZ_1964__86_170321,
     author = {Johann Sonner},
     title = {Universal solutions and adjoint homomorphisms.},
     journal = {Mathematische Zeitschrift},
     pages = {14--20},
     publisher = {mathdoc},
     volume = {86},
     year = {1964},
     zbl = {0135.02104},
     url = {http://geodesic.mathdoc.fr/item/MZ_1964__86_170321/}
}