No. We have a few quotations in other authors of Fabius Pictor, and we know that Livy and others used him as a source. Much the same can be said of Timaeus. We know little about the content of Timaeus than Fabius Pictor even though we have significantly more fragments of Timaeus (well over a hundred). We know that he was used by Diodorus Siculus and Polybius, who began his work where Timaeus left off and included a critique of his history. We know almost nothing about Diocles. We know about Diocles pretty much solely from Plutarch, who mentions that Fabius Pictor used him. Besides that we know pretty much nothing