http://www.documentacatholicaomnia.eu/ With many important links.

http://speedbible.com/vulgate/ The Vulgate (the Latin translation of the Bible by saint Jerome).

http://www.documentacatholicaomnia.eu/25_Migne.html The “Patrologia Latina” by Migne.

http://www.ccel.org/fathers.html The “early Church fathers” translated into English.

http://www.newadvent.org/fathers/ The Church fathers (both Latin and Greek) translated into English.

http://www.tylatin.org/extras/index.html The “Carmina Burana”.

http://ducange.enc.sorbonne.fr/ The “Glossarium mediae et infimae Latinitatis”, by Charles du Fresne lord du Cange (in Latin).

https://archive.org/details/MedievalLatinLexicon A dictionary of medieval Latin (Niermeyer, in French and English).

http://www.hist.msu.ru/Departments/Medieval/Cappelli/ A dictionary of Latin abbreviations (in Italian).