This week Blogging the Beatles is back with the third installment of our “Who Wrote It?” quiz, which asks you who wrote which songs on each album the Beatles made. Fifty years ago this month, the Beatles finished recording their third album, A Hard Day’s Night.

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 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.)

How to tell the difference? One hint: Lennon’s melodies tend to be “horizontal,” in the sense that they move up and down very little, while McCartney’s are generally “vertical,” taking great leaps up and down the scale. Good luck!