  For the study of the bibliological and palaeographical aspects of the Herculaneum papyri, Cavallo 1983 is fundamental, along with Capasso 1991 and Del Mastro 2014. Studies useful for studying the grammar and orthography of Philodemus papyri are found in a number of the introductions to recent editions, especially Obbink 1996 and Janko 2000, in many articles in Cronache Ercolanesi, as well as in Crönert 1903. There are also special lexica: Vooijs 1934, Vooijs-van Krevelen 1941, and Usener 1977.