def illegal_doi(self, doi_string):
        """
        DOI string did not match the regex. Determine what the data is.
        :param doi_string: (str) Malformed DOI string
        :return: None
        """
        logger_doi_resolver.info("enter illegal_doi")
        # Ignores empty or irrelevant strings (blank, spaces, na, nan, ', others)
        if len(doi_string) > 5:

            # NOAA string
            if 'noaa' in doi_string.lower():
                self.noaa_citation(doi_string)

            # Paragraph citation / Manual citation
            elif doi_string.count(' ') > 3:
                self.root_dict['pub'][0]['citation'] = doi_string

            # Strange Links or Other, send to quarantine
            else:
                logger_doi_resolver.warn("illegal_doi: bad doi string: {}".format(doi_string))
        logger_doi_resolver.info("exit illegal_doi")
        return
DOI string did not match the regex. Determine what the data is.
        :param doi_string: (str) Malformed DOI string
        :return: None