www.celtic-languages.org/Welsh/Getting_started - Some information and resources.
www.omniglot.com/writing/welsh.htm - Information, numbers, reources, audio, links, etc.
'Welsh' in The Celtic Languages, Awbery (1993)
Geiriadur Prifysgol Cymru - Dictionary, including historical words and terms, and the etymology and history of words.
Gweiadur - Dictionary, thesaurus, place names, and verb conjugator.
Pocket Modern Welsh Dictionary, by King (2000)
www.celtic-languages.org/Welsh/Resources - Welsh resources, courses, dictionaries, media, etc.
Say Something In Welsh - Audio course that starts at beginner level.
Duome - The grammar notes that were removed from the Duolingo course.
Some basic rules of Welsh grammar
Complete Welsh, by Brake and Jones (2000)
Gramadeg Cymraeg Cyfoes: Contemporary Welsh Grammar, (1998)
Colloquial Welsh: The Complete Course for Beginners, by King (1995)
Welsh in Three Months, by Brake and ap Myrddin (1994)
Teach Yourself Welsh, by Rhys Jones (1992)
A Welsh Grammar, by Williams (1980)
Teach Yourself Welsh, by Bowen and Rhys Jones (1960)
A Grammar of the Welsh Language, Based on the Most Approved Systems, with Copious Examples from Some of the Most Correct Welsh Writers, by Rowland (1853)
www.bbc.co.uk/cymru/cymraeg/safle/tafodiaith/tudalen/y_wenhwyseg.shtml - Gwybodaeth am dafodieithoedd Ynys Môn, gogledd-orllwein, gogledd-ddwyrain, de-orllewin, de-ddwyrain, Gwenhwyseg, y canolbarth, Rhosllannerchrugog, a "Stwnsh neu fwtrin?".
Valleys Welsh - Posts in and about Gwenhwyseg.
kimkat.org - dialects homepage, the Gwenhwyseg dialect, site map
maes-e.com - Fforwm yn Gymraeg.