See E. H. Pagels, The Gnostic Gospels (1979); K. Rudolph, Gnosis (1983); B. Layton, The Gnostic Scriptures (1987); J. M. Robinson, The Nag Hammadi Library in English (1988).
The town of Nag Hammadi was established by Mahmoud Pasha Hammadi, who was a member of the Hammadi family in Sohag, Egypt. Mahmoud Pasha Hammadi was a major landholder in Sohag, and known for his strong opposition to the British occupation.
Mahmoud Pasha Hammadi created Nag Hammadi for the indigenous people from Sohag who were forced to abandon their homeland by the British occupation. In recognition of this, the new town was given the name "Hammadi".
Nag Hammadi is best known for being the site where local farmers found a sealed glass jar containing thirteen leather-bound papyrus codices, together with pages torn from another book, in December 1945. The farmers burned one of the books and parts of a second (including its cover). Thus twelve of these books (one missing its cover) and the loose pages survive. The writings in these codices, dating back to the 2nd century AD, comprised 52 mostly Gnostic tractates (treatises), believed to be a library hidden by monks from the nearby monastery of St Pachomius when the possession of such banned writings, denounced as heresy, was made an offence.
The contents of the Coptic-bound codices were written in Coptic, though the works were probably all translations from Greek. Most famous of these works must be the Gospel of Thomas, of which the Nag Hammadi codices contain the only complete copy.
All the texts have been public since 1975, and are available online (in English, for example, at gnosis.org).