Although free jazz is widely considered to begin in the late 1950s, there are compositions that precede this era that have notable connections to the free jazz aesthetic. Some of the works of Lennie Tristano in the late 1940s, particularly "Intuition", "Digression", and "Descent into the Maelstrom" exhibit the use of techniques associated with free jazz, such as atonal collective improvisation and lack of discrete chord changes. Other notable examples of proto-free jazz include "City of Glass" written in 1948 by Bob Graettinger for the Stan Kenton band and Jimmy Giuffre's 1953 "Fugue". It can be argued, however, that these works are more representative of third stream jazz with its references to contemporary classical music techniques such as serialism.