For the lexicography of pre-Chaghataic Eastern Middle Turkic there exist, besides the texts available, a number of lexicographical works written in the Arabian grammarian tradition. The sources are of good quality, but evaluating them is difficult and time-consuming. A particularly important source was recently discovered and edited, the Kitāb al-afʽāl. The difficulties encountered in working with this type of source is discussed, taking this edition as an example.