@article{GDZPPN002082292, title = {L'H\^opital's rule, a counterexample.}, journal = {Elemente der Mathematik}, volume = {44}, year = {1989}, pages = {116-121}, zbl = {0702.26003}, url = {http://dml.mathdoc.fr/item/GDZPPN002082292} }
Vyborny, R.; Nester, R. L'Hôpital's rule, a counterexample.. Elemente der Mathematik, Tome 44 (1989) pp. 116-121. http://gdmltest.u-ga.fr/item/GDZPPN002082292/