Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
pervŏlūto, āre, v. freq. a. [pervolvo], to roll over and over; hence, in partic., to turn over books, to look through, read: libros, Cic. Att. 5, 12, 2: scriptores, id. de Or. 1, 34, 158.