Exactly where a day is just not known specifically, "c. " might be employed for "circa". Other examples are supplied at WP:APPROXDATE, While "fl. " for "floruit" should be prevented as it is not universally comprehended. Centuries really should not be abbreviated "c. " due to the opportunity for confusion https://kyleruvrlc.blog4youth.com/35969751/detailed-notes-on-youtube