D.D. Krasilnikov and N.N. Efimov

In 1959 D.D. Krasilnikov have formulated an idea of the EAS array in Yakutsk. The construction begun of EAS-13 prototype array consisting of 13 stations in 1966-1967 (D.D. Krasilnikov, I.Ye. Sleptsov).  1969-1970: first showers detected. In 1971 the first stage array constraction begun consisting of 43 scintillator stations, Cherenkov light detectors and a detector of muons (N.N. Efimov). The second stage of the array was completed to 1991 (I.Ye. Sleptsov). Additional experiments have fulfilled to measure neutrons initiated by EAS (1976-1987) and to detect radiosignal from showers (1.9 MHz:1972-1973, 32 MHz: 1986-1989).