Conversation so far:
What is The Citadel in relation to A. J. Cronin?
The Citadel is a novel by A. J. Cronin, first published in 1937, which was groundbreaking in its treatment of the contentious theme of medical ethics.
How did A. J. Cronin draw influence from his novel The Citadel?
Was A. J. Cronin's work accepted?
A. J. Cronin quickly made enemies in the medical profession, and there was a concerted effort by one group of specialists to get the novel The Citadel banned.

Question: What did that group of people do to try and get it banned?
Self-contained rewrite: What did the group of specialists do to try and get A. J. Cronin's novel The Citadel banned?