@misc{ enwiki:1229261131, author = "{Wikipedia contributors}", title = "Yttrium barium copper oxide --- {Wikipedia}{,} The Free Encyclopedia", year = "2024", url = "https://en.wikipedia.org/w/index.php?title=Yttrium_barium_copper_oxide&oldid=1229261131", note = "[Online; accessed 14-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:1229261131, author = "{Wikipedia contributors}", title = "Yttrium barium copper oxide --- {Wikipedia}{,} The Free Encyclopedia", year = "2024", howpublished = "\url{https://en.wikipedia.org/w/index.php?title=Yttrium_barium_copper_oxide&oldid=1229261131}", note = "[Online; accessed 14-July-2024]" }