bool isBibTeX() const { return is_bibtex_; }
private:
/// like operator[], except, if the field is empty, it will attempt
/// to get the data from xref BibTeXInfo object, which would normally
/// be the one referenced in the crossref field.
bool isBibTeX() const { return is_bibtex_; }
private:
/// like operator[], except, if the field is empty, it will attempt
/// to get the data from xref BibTeXInfo object, which would normally
/// be the one referenced in the crossref field.