@misc{ enwiki:1215495289, author = "{Wikipedia contributors}", title = "Variations on a Theme by Haydn --- {Wikipedia}{,} The Free Encyclopedia", year = "2024", url = "https://en.wikipedia.org/w/index.php?title=Variations_on_a_Theme_by_Haydn&oldid=1215495289", note = "[Online; accessed 28-June-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:1215495289, author = "{Wikipedia contributors}", title = "Variations on a Theme by Haydn --- {Wikipedia}{,} The Free Encyclopedia", year = "2024", howpublished = "\url{https://en.wikipedia.org/w/index.php?title=Variations_on_a_Theme_by_Haydn&oldid=1215495289}", note = "[Online; accessed 28-June-2024]" }