Naxos
Fidelio by beethoven. opera libretti. a list of the top opera music composers and their compositions.
http://www.naxos.com/education/opera_libretti.asp?pn=&char=all&composer=beethoven&opera=fidelio&libretto_file=english/0_title_page.htm
Librettidopera
Librettidopera
http://www.librettidopera.it
Ipasource
Word-for-word translations and ipa transcriptions of songs and arias in latin, italian, german, and french in pdf format.
http://www.ipasource.com/opera_libretti
Dmoz
Dmoz
http://www.dmoz.org/Arts/Music/Styles/O/Opera/Libretti
Udel
Udel
http://udel.edu/~lneff/alaegs.htm
Il Trovatore
Il Trovatore
http://www.giuseppeverdi.it/inglese/page.asp?idcategoria=162&idsezione=581&id=19908
Opera
Opera
http://opera.stanford.edu/iu/librettim.html
Online Opera Scores (Algemeen)
Online Opera Scores (Algemeen)
http://www.dlib.indiana.edu/variations/scores/scores.html