@misc{ enwiki:1227639665, author = "{Wikipedia contributors}", title = "Sturm–Liouville theory --- {Wikipedia}{,} The Free Encyclopedia", year = "2024", url = "https://en.wikipedia.org/w/index.php?title=Sturm%E2%80%93Liouville_theory&oldid=1227639665", note = "[Online; accessed 10-July-2024]" }
url
(\usepackage{url}
somewhere in the preamble), which tends to give much more nicely formatted web addresses, the following may be preferred:
@misc{ enwiki:1227639665, author = "{Wikipedia contributors}", title = "Sturm–Liouville theory --- {Wikipedia}{,} The Free Encyclopedia", year = "2024", howpublished = "\url{https://en.wikipedia.org/w/index.php?title=Sturm%E2%80%93Liouville_theory&oldid=1227639665}", note = "[Online; accessed 10-July-2024]" }