Victoria University in Melbourne, Australia, has guidance for citing conference proceedings at http://libraryguides.vu.edu.au/apa-referencing/conference-proceedings
Hope this helps:
The basics of a reference list entry for a paper in a published conference proceedings:
•Author or authors of paper. Surname followed by first initials.
•Year (in round brackets).
•Title of paper.
•Editors of conference proceedings.
•Title of conference proceedings (in italics).
•Pages of paper (in round brackets).
•Location of publisher.
•The first line of each citation is left adjusted. Every subsequent line is indented 5-7 spaces.
Blakey, N., Guinea, S., & Saghafi, F. (2017). Transforming undergraduate nursing curriculum by aligning models of clinical reasoning through simulation. In R. Walker, & S. Bedford (Eds.), HERDSA 2017 Conference: Research and Development in Higher Education: Curriculum Transformation (pp. 25-37). Hammondville, NSW: Higher Education Research and Development Society of Australasia. Retrieved from http://www.herdsa.org.au/research-and-development-higher-education-vol-40-25