NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.
Coffin JM, Hughes SH, Varmus HE, editors. Retroviruses. Cold Spring Harbor (NY): Cold Spring Harbor Laboratory Press; 1997.
Science cannot be divided into what is up to date and what is merely of antiquarian interest; it is to be regarded as the product of a growth of thought.
Peter B. Medawar