@article{HHA_2021_23_1_a4,
     author = {Piotr Bart{\l}omiejczyk and Piotr Nowak-Przygodzki},
     title = {Gradient versus proper gradient homotopies},
     journal = {Homology, homotopy, and applications},
     pages = {61--76},
     publisher = {mathdoc},
     volume = {23},
     number = {1},
     year = {2021},
     doi = {10.4310/HHA.2021.v23.n1.a5},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4310/HHA.2021.v23.n1.a5/}
}