- NLW MSS
- Is-fonds
- [17 cent., first ¼]-[19 cent.].
The Plas Yolyn manuscripts, [17 cent., first ¼]-[19 cent.], comprising manuscripts and correspondence of Morgan Llwyd; correspondence and papers of Colonel John Jones, Maesygarnedd; the correspondence and papers of the family of Colonel John Jones and their associates; papers relating to the Edwards family of Cilhendre; manuscripts and papers relating to the Hanmer family; papers relating to the Morrall family of Cilhendre, Plas Yolyn, and to the sale of Plas Yolyn to William Challnor; miscellaneous manuscripts and papers. The group includes bound volumes as well as family and personal papers subsequently bound at the National Library of Wales.