Information:  - Christianity is a monotheistic religion based on the life and teachings of Jesus Christ, who serves as the focal point for the religion. It is the world's largest religion, with over 2.4 billion followers, or 33% of the global population, known as Christians. Christians believe that Jesus is the Son of God and the savior of humanity whose coming as the Messiah (the Christ) was prophesied in the Old Testament.  - The Wanderings of Oisin is an epic poem published by William Butler Yeats in 1889 in the book "The Wanderings of Oisin and Other Poems". It was his first publication outside magazines, and immediately won him a reputation as a significant poet. This narrative poem takes the form of a dialogue between the aged Irish hero Oisín and St. Patrick, the man traditionally responsible for converting Ireland to Christianity. Most of the poem is spoken by Oisin, relating his three-hundred year sojourn in the isles of Faerie. Oisin has not been a popular poem with critics influenced by modernism, who dislike its pre-Raphaelite character. However, Harold Bloom defended this poem in his book-length study of Yeats, and concludes that it deserves reconsideration.  - The Abbey Theatre, also known as the National Theatre of Ireland, in Dublin, Republic of Ireland, first opened its doors to the public on 27 December 1904. Despite losing its original building to a fire in 1951, it has remained active to the present day. The Abbey was the first state-subsidized theatre in the English-speaking world; from 1925 onwards it received an annual subsidy from the Irish Free State. Since July 1966, the Abbey has been located at 26 Lower Abbey Street, Dublin 1.  - The Wanderings of Oisin and Other Poems was the first collection of poems by W. B. Yeats . It was published in 1889 . In addition to the title poem , the last epic - scale poem that Yeats ever wrote , the book includes a number of short poems that Yeats would later collect under the title Crossways in his Collected Poems .  - William Butler Yeats (13 June 186528 January 1939) was an Irish poet, and one of the foremost figures of 20th-century literature. A pillar of both the Irish and British literary establishments, he helped to found the Abbey Theatre, and in his later years served as an Irish Senator for two terms, and was a driving force behind the Irish Literary Revival along with Lady Gregory, Edward Martyn and others.    Given the paragraphs above, decide what entity has the relation 'author' with 'william butler yeats'.
Answer:
the wanderings of oisin and other poems