@article{GDZPPN002224011, title = {A Solution to a Problem of de Wilde and Tsirulnikov.}, journal = {Manuscripta mathematica}, volume = {39}, year = {1982}, pages = {61-64}, zbl = {0486.46003}, url = {http://dml.mathdoc.fr/item/GDZPPN002224011} }
Drewnowski, Lech. A Solution to a Problem of de Wilde and Tsirulnikov.. Manuscripta mathematica, Tome 39 (1982) pp. 61-64. http://gdmltest.u-ga.fr/item/GDZPPN002224011/