Dr Seuss
Dr Seuss wrote the works contained in A Classic Case of Dr Seuss, which a young Grant had on a shelf in his bedroom. (TV: The Return of Doctor Mysterio)
The Eighth Doctor owned a copy of Seuss' book Green Eggs and Ham, which he once read while simultaneously reading Hospital Station by James White and listening to "We Have All the Time in the World" by Louis Armstrong on repeat. (PROSE: Beltempest) According to the Sixth Doctor there was a planet devoted to the works of Dr Seuss. He had been tempted to go there in the past, especially to try the green eggs and ham. (AUDIO: Trouble in Paradise)
Behind the scenes
The Sixth Doctor wanting to try "green eggs and ham" is in reference to Seuss's book of the same name.
Seuss also created the Grinch, the titular character of his book How the Grinch Stole Christmas!.
John Cleese narrated the story "Did I Ever Tell You How Lucky You Are?" for the "Dr. Seuss Beginner Book Video" series.