Zimmer, C. 2002. Darwin's avian muses continue to evolve. Science 296:633-635.

Pennisi, E. 2004. Bonemaking protein shapes beaks of Darwin's finches. Science 305:1383.

Pennisi, E. 2006. Competition drives big beaks out of business. Science 313:156.

Patel, N. H. 2006. How to build a longer beak.

Just for fun, this is an interview with the Grants from a previous edition of Campbell.