There exists an article on sutta and suttanta in German by Konrad Klaus, "Zu den buddhistischen literarischen Fachbegriffen sutta und suttanta", in  "From Turfan to Ajanta. Felicitation volume in honour of Prof. Schlingloff, ed. E. Franco and Monika Zin, Vol. 1., Lumbini 2010, 513-526.

Best.
Petra