Varrock census records can be obtained in the Varrock Palace library. It is to be given to Reldo so that he can determine where the descendants of Tristan may possibly reside.
Upon reading the census records, a chat box message will appear, stating The book contains page after page of census records. You're sure it makes for a thrilling read but you have better things to be getting on with. Maybe Reldo can read it for you instead.