Abstract — There are solution approaches for several thermal-physical inverse problems discussed in the paper that are based on extension of non-stationery temperature field in the series. An applied method for separation of variables differs from the conventional method for separation of variables. Effect thereof differs as well and is especially convenient for solving inverse thermal-physical problems. Abraham Temkin (1919–2007) created this method for separation of variables. He also offered several methods for solving inverse problems. Those methods are not studied enough and are not known among a wider range of experts. Those methods have been created between 1956 and 1973 and have been published in various journals in Samara, Moscow, Minsk, and Riga. All those publications are in Russian and not available in electronic format.