About the command "\BibTeX"

Question

I'm studying LaTeX now. From a book, I see the symbol BiBTeX

in a section title. Then I want to reproduce it.

%\usepackage{doc}
\section{\BibTeX}
\BibTeX

With above codes, I obtain the following results:

I don't know why BibTeX is not in small capitals shape. The results are different between setion title and normal content.

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From below comments, I think I have known some reasons for the problem. Adding \usepackage[T1]{fontenc} is an anwser.

And I want to ask if my problem above is just caused by the requirement of both small caps and bold as the command \BibTeX is in the curly braces of \section{}