File:Winding Number -1.svgDescriptionWinding Number -1.svg This curve has winding number -1 around the shown point. Source Own work Author Jim.belk
File:Houthalen - Schachttorens.jpgNederlands: Schachttorens voormalige steenkoolmijn van Houthalen English: Winding towers of the former coal mine of Houthalen Magyar: Szénbánya aknatornyai