1. COSPAR Planetary Protection Policy. Approved by the bureau and council, World Space Council, USA 24 March 2011
2. Pierson, D.L.: Microbial contamination of spacecraft. Gravit. Space Biol. Bull. 14(2), 1–6 (2001)
3. Rummel, J., Ehrenfreund, P., Peter, N.: COSPAR workshop on planetary protection for outer planet satellites and small solar system bodies. COSPAR, Paris, 41 (2009)
4. John, D., Rummel, J.: Planetary exploration in the time of astrobiology: protecting against biological contamination. PNAS 98(5), 2128–2131 (2001)
5. Debus, A.: Planetary protection: Elements for cost minimization. Acta Astronaut. 59, 1093–1100 (2006)