A body of written works related by subject-matter (e.g. the literature of computing), by language or place of origin (e.g. Russian literature), or by prevailing cultural standards of merit. In this last sense, ‘literature’ is taken to include oral, dramatic, and broadcast compositions that may not have been published in written form but which have been (or deserve to be) preserved. Since the 19th century, the broader sense of literature as a totality of written or printed works has given way to more exclusive definitions based on criteria of imaginative, creative, or artistic value, usually related to a work's absence of factual or practical reference (see autotelic). Even more restrictive has been the academic concentration upon poetry, drama, and fiction. Until the mid-20th century, many kinds of non-fictional writing—in philosophy, history, biography, criticism, topography, science, and politics—were counted as literature; implicit in this broader usage is a definition of literature as that body of works which—for whatever reason—deserves to be preserved as part of the current reproduction of meanings within a given culture (unlike yesterday's newspaper, which belongs in the disposable category of ephemera). This sense seems more tenable than the later attempts to divide literature—as creative, imaginative, fictional, or non-practical—from factual writings or practically effective works of propaganda, rhetoric, or didactic writing. The Russian Formalists' attempt to define literariness in terms of linguistic deviations is important in the theory of poetry, but has not addressed the more difficult problem of the non-fictional prose forms. See also belles-lettres, canon, paraliterature. For a fuller account, consult Peter Widdowson, Literature (1998).