@article{CM_1969__21_4_349_0, author = {de Groot, J. and Herrlich, H. and Strecker, G. E. and Wattel, E.}, title = {Compactness as an operator}, journal = {Compositio Mathematica}, pages = {349--375}, publisher = {Wolters-Noordhoff Publishing}, volume = {21}, number = {4}, year = {1969}, mrnumber = {259861}, zbl = {0186.55902}, language = {en}, url = {http://archive.numdam.org/item/CM_1969__21_4_349_0/} }