Given a passage and a question, find the answer to the question based on the passage. The answer should consist of only one word that lies in the span of only one of the sentences in the passage.

Paragraph: To Kill a Mockingbird is a novel by Harper Lee published in 1960 . It was immediately successful , winning the Pulitzer Prize , and has become a classic of modern American literature . The plot and characters are loosely based on Lee 's observations of her family , her neighbors and an event that occurred near her hometown of Monroeville , Alabama , in 1936 , when she was 10 years old .
Question: when did to kill a mockingbird come out
1960