def _load_bib_db(self):
<EOL>command = LatexCommand(<EOL>'<STR_LIT>',<EOL>{'<STR_LIT:name>': '<STR_LIT>', '<STR_LIT>': True, '<STR_LIT>': '<STR_LIT:{>'})<EOL>try:<EOL><INDENT>parsed = next(command.parse(self._tex))<EOL>bib_names = [n.strip() for n in parsed['<STR_LIT>'].split('<STR_LIT:U+002C>')]<EOL><DEDENT>except StopIteration:<EOL><INDENT>self._logger.warning('<STR_LIT>')<EOL>bib_names = []<EOL><DEDENT>custom_bib_names = [n for n in bib_names<EOL>if n not in KNOWN_LSSTTEXMF_BIB_NAMES]<EOL>custom_bibs = []<EOL>for custom_bib_name in custom_bib_names:<EOL><INDENT>custom_bib_path = os.path.join(<EOL>os.path.join(self._root_dir),<EOL>custom_bib_name + '<STR_LIT>'<EOL>)<EOL>if not os.path.exists(custom_bib_path):<EOL><INDENT>self._logger.warning('<STR_LIT>',<EOL>custom_bib_path)<EOL>continue<EOL><DEDENT>with open(custom_bib_path, '<STR_LIT:r>') as file_handle:<EOL><INDENT>custom_bibs.append(file_handle.read())<EOL><DEDENT><DEDENT>if len(custom_bibs) > <NUM_LIT:0>:<EOL><INDENT>custom_bibtex = '<STR_LIT>'.join(custom_bibs)<EOL><DEDENT>else:<EOL><INDENT>custom_bibtex = None<EOL><DEDENT>db = get_bibliography(bibtex=custom_bibtex)<EOL>self._bib_db = db<EOL>
r"""Load the BibTeX bibliography referenced by the document.

        This method triggered by the `bib_db` attribute and populates the
        `_bib_db` private attribute.

        The ``\bibliography`` command is parsed to identify the bibliographies
        referenced by the document.