(1) | (book) | Understand Biology for Advanced Level, 4th Edition, Glenn and Susan Toole, Stanley Thornes Press, p.124 - 125 |
(2) | (book) | Advanced Biology, principles and applications, international student edition, by C.J. Clegg with D.G. Mackkean, John Murray, pp. 629 |
(3) | (web) | Cystic Fibrosis Foundation |
(4) | (web) | Kids Health |
(5) | (web) | Medicine Plus |
(6) | (web) | Myoclinic |
(7) | (web) | Wikipedia |
(8) | (web) | MedicineNet |