Sorry, this has been kind of hidden away on the academic page. We’re currently preparing a short technical report for Prodigy, which will be uploaded to arXiv – so for now, you’ll have to use a forward citation:
author = "Montani, Ines and Honnibal, Matthew",
title = "Prodigy: A new annotation tool for radically efficient machine teaching",
journal = "Artificial Intelligence",
volume = "to appear",
year = "2018",
eprint = "to appear"