Desk research is the analysis of documentation sources - external and internal.

Desk research conducted in a secondary data collection method. A large amount of secondary data is within the company itself, and as a first step in the desk research includes organizing internally available. 

A large amount of information available can lead to collecting too much information that they have only a secondary importance. Bearing this in mind, desk research is best entrusted to professional researchers.

Frugality is a good rule in any research: it should only use the information that makes sense.
Lak and Rubin, 1987