Do Users Use a User Guide?  

Technical writers make distinctions between the types of documents they create: user guides, reference manuals, tutorials. But do users really understand these document types? How do users look for different kinds of information--and how do we, as technical writers, make it clear to them what types of information are available? This paper presents results of usability evaluations of documentation for electronic design automation software, showing how a writing team tried to improve the categorization and presentation of document types.

Heninger, Barbara L. and Michael J. Miller. STC Proceedings (2004). Articles>Documentation>User Centered Design>Genre