Levels of Maturity in API Documentation 
This paper proposes a set of API documentation maturity levels that can be used to define a writer or writing team’s ability to document technical materials and to set goals for moving between levels towards more independence from developers. It examines development and documentation team process maturity, as well as several types of API documentation, and their impact on writers new to producing developer documentation. The paper also discusses some of the common difficulties associated with developer-level documentation.
Kozlowski, Paula and Benjamin Dollar. STC Proceedings (2004). Articles>Documentation>Programming