Bibliography

http://www.bbc.co.uk/bitesize/ks3/science/organisms_behaviour_health/life_processes/revision/5/

http://kidshealth.org/kid/htbw/heart.html

http://www.healthhype.com/red-blood-cells-functions-size-structure-life-cycle-pictures.html

http://faculty.ucc.edu/biology-potter/life_cycle_of_the_erythrocyte.htm