Harper Lee does not directly tell the reader what years the novel takes place during. What are some clues that she provides to help the reader determine the time period?

I believe there is a quote, "There is a tendency in this year of grace, 1935..."

There is also mention of the movie Dracula (1931) as well as the "DEWEY DECIMAL SYSTEM" . In Chapter 27 Adolph Hitler rising to power is mentioned which happened around 1933.