Glade, N.; Ballet, P.; Bastien, O. (2012). «A stochastic process approach of the drake equation parameters». International Journal of Astrobiology11 (2): 103–108. doi:10.1017/S1473550411000413. Bibcode: 2012IJAsB..11..103G.
Glade, N.; Ballet, P.; Bastien, O. (2012). «A stochastic process approach of the drake equation parameters». International Journal of Astrobiology11 (2): 103–108. doi:10.1017/S1473550411000413. Bibcode: 2012IJAsB..11..103G. Note: This reference has a table of 1961 values, claimed to be taken from Drake & Sobel, but these differ from the book.
Glade, N.; Ballet, P.; Bastien, O. (2012). «A stochastic process approach of the drake equation parameters». International Journal of Astrobiology11 (2): 103–108. doi:10.1017/S1473550411000413. Bibcode: 2012IJAsB..11..103G.
Glade, N.; Ballet, P.; Bastien, O. (2012). «A stochastic process approach of the drake equation parameters». International Journal of Astrobiology11 (2): 103–108. doi:10.1017/S1473550411000413. Bibcode: 2012IJAsB..11..103G. Note: This reference has a table of 1961 values, claimed to be taken from Drake & Sobel, but these differ from the book.