1. Characterization and molecular cloning of a bovine lentivirus related to human immunodeficiency virus;Gonda;Nature,1987
2. The ‘Pharmers’ who breed cows that can make drugs;Feder;New York Times,1992
3. Gene pharming;Powledge;Technology Review,1992
4. Smallpox vaccine and vaccination in the intensified smallpox eradication programme,1988
5. The global eradication of smallpox,1980