1. Nichols, J.T., Temperature measuring, U.S. Patent no. 2008793, 1935.
2. Beller, W.S., Navy sees promise in infrared thermography for solid case checking, Missiles Rockets, 1965, vol. 16, no. 22, pp. 1234–1241.
3. Green, D.R., Principles and applications of emittance-independent infrared nondestructive testing, Appl. Opt., 1968, vol. 7, no. 9, pp. 1796–1805.
4. Bekeshko, N.A. and Popov, Yu.A., Quality checks of spot welded joints by a thermographic method, Defektoskopiya, 1971, no. 3, pp. 123–127.
5. Vavilov, V.P., Gorbunov, V.I., and Kuznetsov, V.B., A theoretical study of one of the problems of thermal testing of spot weld seams, Defektoskopiya, 1973, no. 1, pp. 21–27.