You ask why the doi
and url
fields don't show up in the formatted bibliographic entries when you use the acm
bibliography style.
The direct answer is, "because the acm
bib style is programmed to recognize and process just the following field types (listed alphabetically): address, author, booktitle, chapter, edition, editor, howpublished, institution, journal, key, month, note, number, organization, pages, publisher, school, series, title, type, volume, and year". Any and all fields names not on this list get ignored.
You might be tempted to ask, "why wasn't the acm
bib style programmed to recognize some other fields, such as doi
and url
? The answer is surprisingly simple: because the acm
style has been around virtually unchanged since 1988, when most people (including, evidently, Oren Patashnik, the creator of BiBTeX and quite a few bib styles) had never heard of dois and URLs.
acm.bst
is a BibTeX style that was last significantly changed in the late 1980s, it neither knows adoi
nor aurl
field. If you want a more modern ACM style, you may want to tryacmart
'sACM-Reference-Format.bst
(ctan.org/tex-archive/macros/latex/contrib/acmart).natbib
and one of its 'standard' styles (e.g.plainnat
). The standardnatbib
styles also know aboutdoi
andurl
. Generally speaking, more modern styles often supportdoi
andurl
, while older styles don't and need workarounds withhowpublished
ornote
.