I think the answer is commas.
Jonas because he is an essential key
Upper class =rich
Middle = in between rich and poor
Lower = poor
Answer: D. McCloud, Alex. How to Teach Your Kids. Eagle Press, 2004.
Explanation: In MLA citation or style of referencing, the authors last name or surname comes first, followed by the first name, then title of the book, journal or source, name of the publisher/s and year or date of publication.