The Project The literary tradition in the third and fourth centuries CE: Grammarians, rhetoricians and sophists as sources of Graeco-Roman literature (FFI2014-52808-C2-1-P) aims to trace and classify all types of quotations, both explicit (with or without mention of the author and/or title) and hidden, in a corpus comprising the Greek grammarians, rhetoricians and " sophists " of the third and fourth centuries CE. At the same time, we try to detect whether or not these are first-hand quotations, and if our quoting authors (28 in all) are, in turn, secondary sources for the same citations in later authors. We also study the philological (textual) aspects of the quotations in their context, and the problems of limits they sometimes pose. Finally, we are interested in the function of the quotation in the citing work. This is the first time that such a comprehensive study of this corpus is attempted. This paper explains our methodology, and how we store all these data in our electronic card-file.