Academia EU. Not read it yet.
https://www.academia.edu/27081447/_From_Terror_to_Tactical_Usage_Elephants_in_the_Partho-Sasanian_Period_The_Parthian_and_Early_Sasanian_Empires_Adaptation_and_Expansion_eds._V._Sarkhosh_Curtis_et._al._Oxford_2016_pp._36-41
I've just got the book from Oxbow - http://www.oxbowbooks.com/oxbow/the-parthian-and-early-sassanian-empires.html
is it worth getting, I have family who need suggests as to what to get me for Christmas etc :-)
Not sure yet - there's a queue.