1. American Library Association. (2017).Selection criteria. Retrieved fromhttp://www.ala.org/tools/challengesupport/selectionpolicytoolkit/criteria
2. American Library Association. (2018a).Frequently challenged books. Retrieved fromhttp://www.ala.org/advocacy/bbooks/frequentlychallengedbooks;
3. American Library Association. (2018b).Top ten most challenged books lists. Retrieved fromhttp://www.ala.org/advocacy/bbooks/frequentlychallengedbooks/top10;
4. Censorship in Three Metaphors