Assuming that you are in search of primary written sources, Linear A tablets, Linear B tablets and the Phaestos Disk are all written archaeological sources that reveal much about the Minoan Civilisation.

The Linear B tablets of Minoa were notably discovered in the palace complexes of Knossos and Khania on Crete. It is widely regarded that these tablets came into widespread use around 1450 B.C.E and have been decoded by Michael Ventris during his investigation of the civilisation in the 1950's. They bear writings which resemble an archaic form of the Greek language and use pictorial symbols in conjunction with letters to record information. The primary use of Linear B tablets was to document administrative and palatial ongoings, which is evidenced by a variety of the tablets themselves which have documented the quantities of goods held in palace magazines (such as wheat and grain) and recorded the distribution of goods from palace to palace across Crete and Minoa. It is widely regarded that a group of trained scribes were responsible for the creation of these tablets at Knossos, this has been noted specifically due to the discovery of 66 varying handwriting scripts identified on the various tablets. The language of Linear B vanished from Minoan and Cretan life after the destruction of Palace Knossos which has been used to further justify the belief that they originated from Knossos.

The Phaestos Disc, additionally, is a round terracotta tablet which has spiralling indentations/ writing marked across it. It contains 241 total images and hieroglyphs on it (with 45 of them being unique). Since its discovery it has been questioned as a legitimate source by various historians and archaeological experts, however historians such as Gareth Owens, Luigi Pernier and Leon Pomerance all have provided evidence on the contrary. Suggestions have been raised that it may have been an inscribed prayer, star chart, or alphabetical record. The Phaestos Disk however has provided information concerning the artistic and linguistic capabilities of the Minoans despite the conjecture and historiographical debate around its use.

Apart from the Linear A tablets of Minoa, primary written sources can be found in the forms of Linear B tablets and the Phaestos Disk.

For additional readings on Minoa I recommend “The Minoans” by George Glasgow and “The Minoans and Mycenaeans: The History of the Civilisations that First Developed Ancient Greek Culture” by The Charles River Historical Editors. Both are relatively comprehensive and concise and provide a good overview of the society and some key sources including frescoes and primary written material.