@article{CM_1971__23_2_155_0,
     author = {Anderson, R. D.},
     title = {Proper homotopies in $l_2$-manifolds},
     journal = {Compositio Mathematica},
     pages = {155--157},
     publisher = {Wolters-Noordhoff Publishing},
     volume = {23},
     number = {2},
     year = {1971},
     mrnumber = {290411},
     zbl = {0218.57007},
     language = {en},
     url = {http://www.numdam.org/item/CM_1971__23_2_155_0/}
}