Journals:

1. Eric L Charnov.Optimal foraging, the marginal value theorem.Theorectical population biology,9(2),1976
2. Graham H. Pyke. OPTIMAL FORAGING THEORY:A CRITICAL REVIEW.Ann. Rev. Ecol. Syst.15(523-75), 1984.
3. G.H.Pyke, H.R Pulliam and E.L. Charnov. Optimal foraging : a selective review of theory and tests, The Quarterly Review of Biology,52,1997

Books:

1. David W. Stephens, Joel Steven Brown, Ronald C. Ydenberg. Foraging:behavior and ecology.Chicago,University of Chicago Press,2007
2. Michael L. Commons, Alejandro Kacelnik, Sara J Shettleworth. Quantitative analysis of behaviour.New Jersey,Lawrence Erlbaum Associates,1987

Webilography:

1. Foraging Behavior : http://people.eku.edu/ritchisong/behavecolnotes2.htm
2. Optimal Foraging Behavior: http://www.thewildclassroom.com/biodiversity/birds/aviantopics/optimalforagingtheory.html
3. Optimal foraging  : http://www.neiu.edu/~jkasmer/Biol380/Labs/optimal.htm
4. Photographic Print of Water shrew : http://www.shopireland.ie/kitchen/detail/B001NT9MJM/photographic-print-of-water-shrew,/
5. Photo by  Alberto Fernandez : http://www.visualphotos.com/image/1x4498779/shrew_crocidura_russula_eating_a_worm
6. Hands-on problem solving : http://www.sinauer.com/ecology/problem05.html