1. B. Oberto, Europa Lander 4-99 SSE roadmap review, JPL Team X Advanced Projects Design Team Study Report, 15 April 1999.
2. B. Oberto, Europa Lander 5-99, JPL Team X Advanced Projects Design Team Study Report, 4 May 1999.
3. National Research Council—Space Studies Board, A Science Strategy for the Exploration of Europa, National Academy Press, Washington, DC, ISBN 0-309-06493-7, 1999.