Query: According to the National Education Association, what was the only book to receive more complaints in 1968?
Context: Upon learning the school administrators were holding hearings to decide the book's appropriateness for the classroom, Harper Lee sent $10 to The Richmond News Leader suggesting it to be used toward the enrollment of "the Hanover County School Board in any first grade of its choice". The National Education Association in 1968 placed the novel second on a list of books receiving the most complaints from private organizations—after Little Black Sambo.