Question: What is the publishing year of this children's book written and illustrated by Dr. Seuss, in which the featured characted was also part of a book "Horton Hatches the Egg"?
{'answer': '1954', 'supporting_facts': [['Horton the Elephant', 0], ['Horton Hears a Who!', 0], ['Horton Hears a Who!', 1]]}