Trilogy and "The Apu Trilogy" of films by Satyajit Ray. Others are connected only by theme: for example, each film of Krzysztof Kieślowski's "Three Colors" trilogy explores one of the political ideals of the French Republic (liberty, equality, fraternity). Trilogies can also be connected in less obvious ways, such as "The Nova Trilogy" of novels by William S. Burroughs, each written using cut-up technique. The term is less often applied to music, such as the "Berlin Trilogy" of David Bowie which is linked together by musical sound and lyrical themes, all having been recorded at least partly in Berlin, Germany. The
San Francisco in the 1970s but also rock music and disco thrived in the city in the 1970s, and from the late 1970s onwards San Francisco also became a major focal point in the North American and international punk, thrash metal, and rave scenes. In 1967, thousands of young people had entered the Haight-Ashbury district during what became known as the Summer of Love. The San Francisco Sound emerged as an influential force in rock music, with such acts as Jefferson Airplane and the Grateful Dead achieving international prominence. These groups blurred the boundaries between folk, rock and jazz traditions and further developed rock's lyrical