Research into how API documentation fails

There isn’t a great deal of research into API documentation, and the factors that make API content good or bad. Here’s some of the papers we’ve found so far:

• How API documentation fails. Research by Uddin and Robillard, McGill University, 2015.

• Creating and Evolving Developer Documentation: Understanding the Decisions of Open Source Contributors, Dagenais and Robillard, 2010.
• How API documentation can be effective and useful (in German). 12 month research project by Prof. Michael Meng et al. Merseburg University of Applied Sciences, Germany, 2016.

Do you know of any others?