1. HH Barshall .1986a .The cost-effectiveness of physics journals .Physics Today,41:56 -59 .
2. HH Barshall .1986b .The cost of physics journals .Physics Today,39:34 -36 .
3. CT Bergstrom, and TC Bergstrom .2004 .The costs and benefits of library site licenses to academic journals .P Nat Acad Sci USA,101:897 -902 .
4. TC Bergstrom .2001 .Free labor for costly journals? J Econ Perspect,15:183 -98 .
5. C. Darwin, 1844a .Observations on the structure and propagation of the genus Sagitta .Ann Mag Nat Hist,13:1 -6 .