The Allen and Greenough is still under construction;
so some links may not work quite the way you would expect.
197. Several verbs add some of the personal endings
of the present system directly to the root,[These are athematic verbs,
see § 174. 2.] or combine two verbs in their inflection. These are
called Irregular Verbs. They are sum,
voló, feró, edó, dó, eó, queó,
fió, and their compounds.
Sum has already been inflected in