The first phase of the rebetiko revival can perhaps be said to have begun around 1960. In that year the singer Grigoris Bithikotsis recorded a number of songs by Markos Vamvakaris, and Vamvakaris himself made his first recording since 1954. During the same period, writers such as Elias Petropoulos began researching and publishing their earliest attempts to write on rebetiko as a subject in itself. The bouzouki, unquestioned as the basic musical instrument of rebetiko music, now began to make inroads into other areas of Greek music, not least due to the virtuosity of Manolis Chiotis. From 1960 onwards prominent Greek composers such as Mikis Theodorakis and Manos Hatzidakis employed bouzouki virtuosi such as Manolis Chiotis, Giorgos Zambetas, and Thanassis Polyhandriotis in their recordings.