I have a .rst document containing the following lines...
This example goes over the analysis found the author's paper [Hughes2017]_.
.. [Hughes2017] Hughes, M., Olsen, J., *On the potential of organic Rankine cycles for recovering waste heat from the exhaust gases of a piston aero-engine*, Asia-Pacific International Symposium on Aerospace Technology, Seoul, Korea, 2017.
When I use Sphinx to produce a .html file from this .rst file, the reference comes out as [Hughes20170] (both in text and in the reference list). Could anybody explain why this is?