In "The Oxford Encyclopedia of British Literature", Kevin Dettmar writes that "Sgt. Pepper" achieved "a combination of popular success and critical acclaim unequaled in twentieth-century art ... never before had an aesthetic and technical masterpiece enjoyed such popularity." Through the level of attention it received from the rock press and more culturally elite publications, the album achieved full cultural legitimisation for pop music and recognition for the medium as a genuine art form. Riley says that pop had been due this accreditation "at least as early as "A Hard Day's Night" in 1964. He adds that the timing of the album's release and its reception ensured that "Sgt. Pepper" has attained the kind of populist adoration that renowned works often assume regardless of their larger significance – it's the Beatles' 'Mona Lisa'." At the 10th Annual Grammy Awards in March 1968, "Sgt. Pepper" won awards in four categories: Album of the Year; Best Contemporary Album; Best Engineered Recording, Non-Classical; and Best Album Cover, Graphic Arts. Its win in the Album of the Year category marked the first time that a rock LP had received this honour.