1. Borovik, V.N. and Livshits, M.A., A Change in the Solar Radio Radius When Coronal Hole Appears on the Limb, Astron. Zh., 1982, vol. 59, no. 2, pp. 355–364.
2. Borovik, V.N., Medar’, V.G., and Garaimov, V.I., Small-Scale Structure of the Microwave Emission of Coronal Holes and Undisturbed Sun according to the RATAN-600 Observations, Trudy mezhdunarodnoi konferentsii “Solntse v maksimume aktivnosti i solnechno-zvezdnye analogi” (Proc. International Conference “The Sun at an Activity Maximum and Solar-Stellar Analogs”), Pulkovo, 2000, pp. 112–114.
3. Ferguson, B.G., Central Meridian Passage Dates of Coronal Holes, Inferred from East-West Solar Scans at 692 and 1415 MHz, for the Period January 1968–January 1974, Sol. Phys., 1981, vol. 69, no. 1, pp. 185–209.
4. Fürst, E. and Hirth, W., A coronal Hole Observed at 10.7 GHz with a Large Single Dish, Sol. Phys., 1975, vol. 42, no. 1, pp. 157–161.
5. Shibasaki, K., Ishiguro, M., and Enome, S., Coronal Hole Observed with a 2.8-cm Radioheliograph, Publ. Astron. Soc. Japan, 1978, vol. 30, no. 4, pp. 589–600.