Lazarus, D. R. and Hawkins, Gerald S. 1963. Meteor Ionization and the Mass of Meteoroids. Proceedings of the symposium on the astronomy and physics of meteors, 7(1): 221-228.
Southworth, Richard B. and Hawkins, Gerald S. 1963. Statistics of Meteor Streams. Proceedings of the symposium on the astronomy and physics of meteors, 7(1): 261-285.
Lazarus, D. R. and Hawkins, Gerald S. 1963. "Meteor Ionization and the Mass of Meteoroids." from Proceedings of the symposium on the astronomy and physics of meteors. 7 (1), 221–228. Washington, D.C.: Smithsonian Institution. Smithsonian Contributions to Astrophysics.
Southworth, Richard B. and Hawkins, Gerald S. 1963. "Statistics of Meteor Streams." from Proceedings of the symposium on the astronomy and physics of meteors. 7 (1), 261–285. Washington, D.C.: Smithsonian Institution. Smithsonian Contributions to Astrophysics.