This week we’re back with the fourth installment of our “ Who Wrote It? ” quizzes , which ask you who wrote which songs on each album the Beatles made. Fifty years ago this month, the Beatles’ Revolver was on the top of the Billboard album chart.

Of course, determining the authorship of Beatles songs can be a little tricky—especially since so much of their best songwriting was collaborative—but we’ve checked all our answers against not only the research of Beatle historians but the words of the songwriters themselves. Note that, when it comes to Lennon–McCartney collaborations, we’re asking for the primary author. For example, a song written 95 percent by McCartney is a McCartney song. For a true 50-50 collaboration, written (as Lennon described the process) “eyeball to eyeball,” the correct answer is “both.” (And in very rare cases where the answer is disputed, we’ve been nice enough to allow for more than one correct answer.)