Many thanks to Marion Rastelli - I now have the article, attached here in case anyone else is also interested.
Dear colleagues,
I'm searching for the following article. If anyone has a PDF copy to share, I'd be most grateful.
Hacker, Paul (1960). 'Zur Entwicklung der Avatàralehre', Wiener Zeitschrift fiir die Kunde Siid- und Ostasiens und Archiv für indische Philosophie 4, pp. 47-70. HV (1936).
Many thanks in advance,
Arti
Arti Dhand
Associate Professor
Department for the Study of Religion
University of Toronto