Use pybtex to validate that a reference is in proper BibTeX format

    Args:
        reference: A String reference in BibTeX format.

    Returns:
        Boolean indicating if reference is valid bibtex.

def is_valid_bibtex(reference):
    """
    Use pybtex to validate that a reference is in proper BibTeX format

    Args:
        reference: A String reference in BibTeX format.

    Returns:
        Boolean indicating if reference is valid bibtex.
    """
    # str is necessary since pybtex seems to have an issue with unicode. The
    # filter expression removes all non-ASCII characters.
    sio = StringIO(remove_non_ascii(reference))
    parser = bibtex.Parser()
    errors.set_strict_mode(False)
    bib_data = parser.parse_stream(sio)
    return len(bib_data.entries) > 0