Note: Certain mutated forms of some words can never occur in standard Welsh.
All possible mutated forms are displayed for convenience.

1. ^R. J. Thomas, G. A. Bevan, P. J. Donovan, A. Hawke et al., editors (1950–present), “iwrch”, inGeiriadur Prifysgol Cymru Online (in Welsh), University of Wales Centre for Advanced Welsh & Celtic Studies
2. ^Cymdeithas Edward Llwyd (1994),Creaduriaid Asgwrn-Cefn: pysgod, amffibiaid, ymlusgiaid, adar a mamaliaid [Vertebrates: fish, amphibians, reptiles, birds and mammals] (Cyfres Enwau Creaduriaid a Planhigion; 1)‎^[1] (in Welsh), Tal-y-bont:Y Lolfa,→ISBN, page44