In 2009 OCLC, the world's largest library cooperative, commissioned a survey of scholars to get an idea of the practical techniques most commonly used in the process of doing research. Here is a summary view in a schematic format.
Source: Palmer, Carole L., Lauren C. Teffeau, and Carrie M. Pirmann. Scholarly Information Practices in the Online Environment Themes from the Literature and Implications for Library Service Development. 2009. 7 May 2009 <http://www.oclc.org/programs/publications/reports/2009-02.pdf>.