Westall, F., Brack, A., Hofmann, B., Horneck, G., Kurat, G., Maxwell, J., Ori, G., G., Pillinger, T., C., Raulin, F., Thomas,
N., Fitton, B., Clancy, & P., (2000). An ESA study for the search for life on Mars. Planetary and Space Science, 48, 181-202.