стиль нагрудника для превращения в капитал книжных заголовков, но не бумажных [закрытых] заголовков

I've checked this against the contents of the plain.bst file, rather thanrelying on dimly recalled assertions about what bibtex does, as per the post of mine I deleted... plain.bst treats titles in one of two ways, using the functions it defines, first, format.title, used, e.g., for @article, which lowercases, and then format.btitle, used for @book, which puts the title in emphasis without touching the capitalisation.

Rules for capitalising titles are complex, complex enough that one can't expect a .bst file to completely automate it. For example, Chicago Manual of Style says one should "Lowercase prepositions, regardless of length" with a list of examples. But prepositionhood is a semantic role, that is syntactically generative: CMoS gives as an example preposition "according to". And one of the exceptions is to capitalise when the preposition is stressed: e.g., in "Alice Through the Looking Glass", where stress isn't even semantic, but a pragmatic property of the word. So it's not the bst's role.

So the Right Thing is to put title strings in title case, protecting the capitalisation of proper names with {}s (e.g., From {B}rouwer to {H}ilbert). Do this with articles too, since some reflist styles, e.g., MLA, put article titles into title case, but most scientif styles lowercase them.

plain.bst gets one thing wrong: for @article, it does not consider colons, which are used to indicate subtitles. So protect the capital letter after colons.

Есть инструмент для генерации пользовательских библи-стилей, makebst.tex . Когда я запускаю его как

latex /usr/share/texmf-texlive/tex/latex/custom-bib/makebst.tex 

он задает много вопросов, и в частности, позволяет выбрать заглавные буквы article title:

CAPITALIZATION OF ARTICLE TITLE:
(*) Sentence style (capitalize first word and those in braces)
(t) Title style (just as in bib entry)
  Select:

\ans=t 
  You have selected: Title style

Нет такой возможности для названий книг.... Но даже в этом случае стиль "Title" означает только "точно так же, как в записи с нагрудником". Так что, наверное, вам нужно вручную сделать заглавные буквы для названий.