The website of the National Gallery of Art has a nice feature about a Cézanne sketchbook. He kept many sketchbooks,  but most of them were taken apart and sold to collectors as individual drawings. The National Gallery has one of the only intact sketchbooks.

In conjunction with the exhibition Cézanne Portraits (March 25–July 1, 2018) this feature offers a selection of drawings of heads and faces from the sketchbook, primarily those of his wife Hortense Fiquet and their son Paul. The drawings date from the late 1870s, when Cézanne was in Paris, to the end of the 1890s, when he had returned to live in his native Aix-en-Provence. These quick sketches were not generally the result of formal portrait sessions, but were made at home, providing a glimpse of the intimacy of his family life.

See more at: Cézanne Sketchbook