https://www.ixtheo.de/
Inde Theologicus
Index Theologicus
https://ixtheo.de/MyResearch/Home?redirect=0
Indexes. Micrologus I (1993) – 28 (2020). Micrologus Library vols I-99
http://www.sismel.info/books/INDICI_M_ML_OA.pdf
Institut für assyriologie hethitologogie LMU – Münche
https://www.assyriologie.uni-muenchen.de/index.html
Internet archive (Digital library of free books, music, movies)
https://archive.org/index.php
Internet culturale
http://www.internetculturale.it/
Internet Encyclopedia of philosophy
https://www.iep.utm.edu/
Internet medieval sourcebook
https://sourcebooks.fordham.edu/sbook.asp
Intra text digital library
http://www.intratext.com/
Io resto a casa
https://www.cittanuova.it/iorestoacasa-citta-nuova/?ms=003&se=025