1. H.T. Friis, A note on a simple transmission formula. Proc. IRE Waves Electron. 34, 254–256 (1946)
2. H.L. Bertoni, Radio Propagation for Modern Wireless Systems (Prentice-Hall, Upper Saddle River, NJ, 2000)
3. P.L. Rice, A.G. Longley, K.A. Norton, A.P. Barsis, Transmission loss predictions for tropospheric communication circuits. Natl. Bur. Stand. Tech. Note 101. I & II (1965)
4. A.G. Longley, P.L. Rice, Prediction of tropospheric radio transmission loss over irregular terrain. ESSA Technical Report ERL 79-ITS 67, U.S. Government Printing Office, July 1968.
5. G.A. Hufford, A.G. Longley, W.A. Kissick, A guide to the use of the ITS Irregular Terrain Model in the area prediction mode. U.S. Department of Commerce, DC, USA, April (1982). [Online]. Available: http://www.ntia.doc.gov/files/ntia/publications/ntia_82-100_20121129145031_555510.pdf .