Lin, F. H.and H. Thormar. Properties of Maedi Nucleic Acid and the Presence of Ribonucleic Acid- and Deoxyribonucleic Acid-dependent Deoxyribonucleic Acid Polymerase in the Virions. American Society for Microbiology, 1972, doi:10.1128/jvi.10.2.228-233.1972.