This was a poster presentation of the full published paper mentioned here.
Citeable as
Hugh J. Paterson III (2015) Phonetic transcription of tone in the IPA. Poser presentation at ICPhS 2015. 18th International Conference of Phonetic Sciences. University of Glasgow: Glasgow, UK.
Though you should probably just cite the paper which is citeable as:
Hugh J. Paterson III (2015) Phonetic transcription of tone in the IPA. In The Scottish Consortium for ICPhS 2015 (Ed.). Proceedings of the 18th International Conference of Phonetic Sciences Paper number 507.1-5. University of Glasgow: Glasgow, UK.