Open Problem Garden

Trouble with ~ in \href links

I encountered a strange behavior with "~" symbol in the \href links. Please take a look at Erdos et al. paper in the bibliography of http://garden.irmacs.sfu.ca/?q=op/divisibility_of_central_binomial_coefficients When I click on this paper link, "~" is substituted with "%C2%A0", resulting in a wrong url. If I replace "~" with "%7E", the link does not work either with even worse corruption of the whole bibliography. So, what is a proper way to specify "~" in the \href links? Thanks, Max P.S. The forum displays this message incorrectly. ;(((