@Incollection{, title = {The topological work of Henri Poincar{\'e}}, author = {Sarkaria, Karanbir S.}, booktitle = {History of topology}, year = {1999}, publisher = {North-Holland, Amsterdam}, pages = {123{\textendash}167}, url = {http://dx.doi.org/10.1016/B978-044482375-5/50007-9} }