Vatican City: Typis Polyglottis Vaticanis, 1960-present. 26 volumes.
The records of the commissions which prepared draft documents for the Council. Includes the full-text of submissions from bishops around the world. Some volumes have been digitized.
Edited by Giuseppe Alberigo.
Maryknoll, NY: Orbis, 1995-2004. 5 volumes.
The definitive history of the Council. Particularly useful for explanations of the organizational structure. Volume 2 (Session 1).is available on the Internet Archive, a trusted source, but one for which it is necessary to create a free account and login.