Rees, Thomas & John Thomas.Hanes Eglwysi Annibynnol Cymru (History of the Welsh Independent Churches), 4 volumes (published 1871+). Here is the entry from this book for Henryd chapel (in Welsh ) - with translation by Eleri Rowlands (April 2012)
Church and chapel data from The Religious census of 1851 : A Calendar of the returns relating to Wales, Vol 11, North Wales. Ed. by Ieuan Gwynedd Jones, UWP,1981. The names given towards the end of each entry are those of the informants.
Llangelynin Parish; Statistics; Area 2017 acres; Population 103 males, 101 females, total 204