Snyder, Gregory K.; Sheafor, Brandon A. (1999). "Red Blood Cells: Centerpiece in the Evolution of the Vertebrate Circulatory System". Integrative and Comparative Biology. 39 (2): 189. doi:10.1093/icb/39.2.189. "BBC Bitesize – GCSE Biology ...
Snyder, Gregory K.; Sheafor, Brandon A. (1999). "Red Blood Cells: Centerpiece in the Evolution of the Vertebrate Circulatory System". Integrative and Comparative Biology. 39 (2): 189. doi:10.1093/icb/39.2.189. "BBC Bitesize – GCSE Biology ...