During his period at SEMA, Villa-Lobos composed five string quartets, nos. 5to9, which explored avenues opened by his public music that dominated his output. He also wrote more music for Segovia, the "Cinq préludes", which also demonstrate a further formalisation of his composition style. After the fall of the Vargas government, Villa-Lobos returned full-time to composition, resuming a prolific rate of completing works. His concertos—particularly those for the classical guitar, the harp, and the harmonica—are examples of his earlier "poema" form. The Harp Concerto is a large work, and shows a new propensity to focus on a small detail, then to fade it and bring another detail to the foreground. This technique also occurs in his final opera, "Yerma", which contains a series of scenes each of which establishes an atmosphere, similarly to the earlier "Momoprecoce".