Bevilacqua, R.; et al, Resonances and close approaches. I - The Titan-Hyperion case, Laboratorio di Astrofisica Spaziale di Frascati, European Workshop on Planetary Sciences, Rome, Italy, Apr. 23-27, 1979 22 (2): 141, April 1980, Bibcode:1980M&P....22..141B, S2CID 119442634, doi:10.1007/BF00898423.
Bevilacqua, R.; et al, Resonances and close approaches. I - The Titan-Hyperion case, Laboratorio di Astrofisica Spaziale di Frascati, European Workshop on Planetary Sciences, Rome, Italy, Apr. 23-27, 1979 22 (2): 141, April 1980, Bibcode:1980M&P....22..141B, S2CID 119442634, doi:10.1007/BF00898423.
Bevilacqua, R.; et al, Resonances and close approaches. I - The Titan-Hyperion case, Laboratorio di Astrofisica Spaziale di Frascati, European Workshop on Planetary Sciences, Rome, Italy, Apr. 23-27, 1979 22 (2): 141, April 1980, Bibcode:1980M&P....22..141B, S2CID 119442634, doi:10.1007/BF00898423.