1. Outage of the L4 System and the Geomagnetic Disturbances of 4 August 1972;Anderson;The Bell System Tech. J.,1974
2. Coffey , H. E. Collected Data Reports on August 1972 Solar-Terrestrial Events NOAA, US Dept. Commerce Boulder, CO. 1973
3. Sugiura , M. D. J. Poros Hourly equatorial Dst values (provisional) H. E. Coffey NOAA, US Dept of Commerce 1973