Question: "Back in the U.S.S.R." is a 1968 song by the Beatles, it is credited to the songwriting partnership Lennon–McCartney, but written by who?

full_context: Document 1: Revolution (Beatles song): "Revolution" is a song by the Beatles, written by John Lennon and credited to Lennon–McCartney. Three versions of the song were recorded in 1968: a slow, bluesy arrangement (titled "Revolution 1") for the Beatles' self-titled double album, commonly known as "the White Album"; a more abstract musical collage (titled "Revolution 9") that originated as the latter part of "Revolution 1" and appears on the same album; and a faster, hard rock version similar to "Revolution 1", released as the B-side of the "Hey Jude" single. Although the single version was issued first, it was recorded several weeks after "Revolution 1", as a re-make specifically intended for release as a single.
Document 2: Dear Prudence: "Dear Prudence" is a song by the English rock group the Beatles from their 1968 album "The Beatles" (also known as "the White Album"). The song was written by John Lennon, and credited to Lennon–McCartney. Written in India, it was inspired by Prudence Farrow, a sister of actress Mia Farrow, who became obsessive about meditating while practising with Maharishi Mahesh Yogi.
Document 3: A Beginning: "A Beginning" is an instrumental piece composed by the Beatles' producer George Martin and intended as an introduction to "Don't Pass Me By", Ringo Starr's first solo composition from the Beatles' 1968 double album "The Beatles" (also known as the "White Album").
Document 4: Within You Without You: "Within You Without You" is a song written by George Harrison and released on the Beatles' 1967 album "Sgt. Pepper's Lonely Hearts Club Band". It was Harrison's second composition in the Indian classical style, after "Love You To", and was inspired by his six-week stay in India with his mentor and sitar teacher, Ravi Shankar, over September–October 1966. Recorded in London without the other Beatles, the song features Indian instrumentation such as sitar, dilruba and tabla, and was performed by Harrison and members of the Asian Music Circle. The recording marked a significant departure from the Beatles' previous work; musically, it evokes the Indian devotional tradition, while the overtly spiritual quality of the lyrics reflects Harrison's absorption in Hindu philosophy and the teachings of the Vedas. Although the song was his only composition on "Sgt. Pepper", Harrison's endorsement of Indian culture was further reflected in the inclusion of yogis such as Paramahansa Yogananda among the crowd depicted on the album cover.
Document 5: The Beatles (album): The Beatles, also known as the White Album, is the ninth studio album by English rock group the Beatles, released on 22 November 1968. A double album, its plain white sleeve has no graphics or text other than the band's name embossed, which was intended as a direct contrast to the vivid cover artwork of the band's earlier "Sgt. Pepper's Lonely Hearts Club Band". Although no singles were issued from "The Beatles" in Britain and the United States, the songs "Hey Jude" and "Revolution" originated from the same recording sessions and were issued on a single in August 1968. The album's songs range in style from British blues and ska to tracks influenced by Chuck Berry and by Karlheinz Stockhausen.
Document 6: There's a Place: "There's a Place" is a song co-written by John Lennon and Paul McCartney, and was first released as a track on the Beatles' debut LP, "Please Please Me". Lennon and McCartney share lead vocals, with George Harrison providing backing vocals. In the US it was released on "Introducing... The Beatles" (Vee-Jay Records) and as the B-side of "Twist and Shout", and was finally released by Capitol Records on "Rarities" in 1980.
Document 7: Lucy in the Sky with Diamonds: "Lucy in the Sky with Diamonds" is a song credited to Lennon–McCartney that appears on the Beatles' 1967 album "Sgt. Pepper's Lonely Hearts Club Band". It was started by John Lennon, then Paul McCartney contributed to it in a songwriting session. Lennon's son Julian inspired the song with a nursery school drawing he called "Lucy—in the sky with diamonds". Shortly after the song's release, speculation arose that the first letter of each of the title nouns intentionally spelled "LSD". Lennon consistently denied this, insisting the song's fantastical imagery was inspired by Lewis Carroll's "Alice in Wonderland" books, a claim repeatedly confirmed by Paul McCartney.
Document 8: Rocky Raccoon: "Rocky Raccoon" is a song by the Beatles from the double album "The Beatles" (also known as the "White Album"). The song was primarily written by Paul McCartney, who was inspired while playing acoustic guitar with John Lennon and Donovan in India (where the Beatles had gone on a retreat).
Document 9: Return to Pepperland: Return to Pepperland is a cancelled Paul McCartney album recorded in 1984–1987. The album was built up of mostly home demos and was a reflection of work from McCartney's career as a member of the English rock band the Beatles. Although it was made around twenty years after the release of the Beatles' 1967 album "Sgt. Pepper's Lonely Hearts Club Band" (which inspired it), some tracks which made their way onto the bootleg were written whilst McCartney was in the Beatles, including the Lennon–McCartney-written "Love Me Do" and "P.S. I Love You". Other songs turned up on CD-single B-sides including the McCartney/Stewart song "Don't Break the Promise".
Document 10: Rock 'n' Roll Music (album): Rock 'n' Roll Music is a compilation album by The Beatles that consists of previously released Beatles tracks. The double album was issued on 7 June 1976 in the United States, on Capitol Records (catalogue number SKBO 11537), and on Parlophone (PCSP 719) in the United Kingdom, four days later. The album is a combination of some notable Lennon–McCartney originals, such as "Drive My Car", "Revolution", "Back in the U.S.S.R." and "Get Back", George Harrison's "Taxman", and a dozen cover versions of songs written by significant rock and roll composers of the 1950s, including Chuck Berry, Little Richard, Carl Perkins and Larry Williams. "Rock 'n' Roll Music" was the first Beatles album to include "I'm Down", which had previously only been available as the B-side of the "Help!" single.
Document 11: Back in the USSR (disambiguation): "Back in the U.S.S.R." is a 1968 song by the Beatles.
Document 12: Get Back: "Get Back" is a song recorded by the Beatles and written by Paul McCartney (though credited to Lennon-McCartney), originally released as a single on 11 April 1969 and credited to "The Beatles with Billy Preston." A different mix of the song later became the closing track of "Let It Be" (1970), which was the Beatles' last album released just after the group split. The single version was later issued on the compilation albums "1967–1970", "20 Greatest Hits", "Past Masters", and "1".
Document 13: Back in the U.S.S.R.: "Back in the U.S.S.R." is a song by the Beatles. It is credited to the songwriting partnership Lennon–McCartney, but written by Paul McCartney. The song opens the 1968 double-disc album "The Beatles" (also known as the "White Album"), and then segues into "Dear Prudence".
Document 14: Got to Get You into My Life: "Got to Get You into My Life" is a song by the Beatles, first released in 1966 on the album "Revolver". It was written by Paul McCartney, though officially credited to Lennon–McCartney. The song is a homage to the Motown Sound, with colourful brass instrumentation, and lyrics that suggest a psychedelic experience. "It's actually an ode to pot," McCartney explained. A cover version by Cliff Bennett and the Rebel Rousers peaked at number six in 1966 in the UK. The song was issued in the United States as a single from the "Rock 'n' Roll Music" compilation album in 1976, six years after the Beatles disbanded. It reached number seven on the "Billboard" Hot 100 chart, the Beatles' last top ten US hit until their 1995 release "Free as a Bird".
Document 15: Sgt. Pepper's Lonely Hearts Club Band (song): "Sgt. Pepper's Lonely Hearts Club Band" is a song written by Paul McCartney (credited to Lennon–McCartney), and first recorded and released in 1967, on the album of the same name by the Beatles. The song appears twice on the album: as the opening track (segueing into "With a Little Help from My Friends"), and as "Sgt. Pepper's Lonely Hearts Club Band (Reprise)", the penultimate track (segueing into "A Day in the Life"). As the title song, the lyrics introduce the fictional band that performs on the album.
ground_truth: Paul McCartney