The situation changed in the early 19th century. Instruction books with exercises became very common. Of particular importance were collections of "studies" by Johann Baptist Cramer (published between 1804 and 1810), early parts of Muzio Clementi's "Gradus ad Parnassum" (1817–26), numerous works by Carl Czerny, Maria Szymanowska's "Vingt exercises et préludes" (c. 1820), and Ignaz Moscheles' "Studien" Op. 70 (1825–26). However, with the late parts of Clementi's collection and Moscheles' "Charakteristische Studien" Op. 95 (1836–37) the situation began to change, with both composers striving to create music that would both please the audiences in concert and serve as a good teaching tool. Such a combination of didactic and musical value in a study is sometimes referred to as a concert study.