Refer to conference proceedings published in hard copy in a collection in the same way as a chapter in a collected work.
John, S., Pedro, J., & Nyandoro, O. T. C. (2012). Development of a model-based wheel slip control using feedback linearization. In D. M. Madyira, N. Janse van Rensburg, & A. J. Nel, (Eds.), Conference proceedings (pp. 37-43). 8th South African Conference on Computational and Applied Mechanics (SACAM 2012), Johannesburg, South Africa. South African Association for Computational and Applied Mechanics.
(John et al., 2012).
Many organisations publish their conference presentations on their web pages.
Schlünz, G. I., & Barnard, E. (2013). A discourse model of affect for text-to-speech synthesis. Paper delivered at the 24th annual Symposium of the Pattern Recognition Association of South Africa, Pretoria. http://www.prasa.org/proceedings/2013/prasa2013-14.pdf
(Schlünz, & Barnard, 2013).