Georgi Nadjakov	Emil Djakov	Evgeni Leyarovski	Konstantin Stamenov

Micro Amper Meter, Stock № 9395, 31.І.1966 г. Production № 20343/ 0.1 - 1 Micro Amper, М95, came from Dr. S. Balabanov during 2016.

Volt Meter, Norma, Production № 1068509; 75 V, 150V, 300 V, 750 V; Institute of Physics Stock № 2529, came from Dr. S. Balabanov during 2016.

Brightness Spot Meter, Spectra, USA; 29.2.1988, Stock № 30001, came from Dr. S. Balabanov during 2016.