  The dating of the composition of the Abstractiones appears to have been around the 1230's or 40's. Earliest references to the Abstractiones appear from the late thirteenth century in a manuscript at Worcester Cathedral Library, Q. 13, which is confidently dated no later than 1295, and probably as early as   1270.[4]   Worcester Q. 13 contains four references to the “Magister Abstractionum.” Another reference to the Abstractiones can be found in a Quodlibetal Question of William of Alnwick, “Does God know infinitely many things (Utrum Deus cognoscat infinita)?”, q. 9 probably dating from around 1320. Walter Burley's tract, De Exceptivis, edited by L. M. de Rijk, contains a reference to the Magister   Abstractionum.[5]  An interesting reference can also be found in William of Ockham's Summa Logicae and additional references can be found in Ps. Richard of Campsall, John of Reading and Adam   Wodeham.[6]