The Differences in the Gospels and their Solutions by Eusebius of Caesarea is quoted all over the place. One stray quotation appears in the letters of Isidore of Pelusium. In the Migne edition this is book 2, letter 212, (PG 78, col. 651). This letter consists entirely of a quotation from the Quaestiones Ad Marinum; how can we say that Jesus was dead for 3 days? The text here is of course a corrective for that published by Mai, and I must send it to my translator.