Many specialised books have been written on the coins of Magna Graecia . Also the Sylloge Nummorum Graecorum series offer much information. General works on Greek coins generally cover the coins of the whole Greek world.
What is missing is an overview, an up to date list of all the published Greek coin types with up to date information concerning the time they were issued and their denomination.
The Sicilian Greeks issued for the first time token bronze coins. Their smallest denomination was an onkia that was equivalent with 0.07 grammes of silver. A litra valued 12 onkiae. The catalogue of the Greek Coins in the British Museum (Volume 2 Sicily, 1876) erroneously describes the denomination trias as equivalent with three onkiae and the tetras as equivalent with four onkiae. Trias, however, means a third of a litra so four onkiae and tetras means a quarter of a litra so three onkiae. In many even recent books this error is still made.
The lists of coin types offered in these WWW pages is ment to give an up to date overview. Moreover, I hope that these pages will lead to remarks, additions and discussions by the readers so that these lists will be updated all the time.