1. http://www.eebweb.arizona.edu/Courses/ecol409_509/Frank02.pdf
2.http://link.springer.com/article/10.1023%2FB%3ABIBU.0000049725.00467.06?LI=true
3.http://health.usf.edu/nocms/publicaffairs/now/natureimmunologycommentary_6-07.pdf
4. http://www.cs.unm.edu/~forrest/classes/immuno-class/readings/EconomicsOfImmunity.pdf