Cramer, Jefrey S., Robert Frost Among His Poems, Jefferson, NC: McFarland & Co. Inc., 1996.
Cramer gives a brief but thorough background of almost every poem Frost has written. An indispensable guide.
Johnson, Paul, Modern Times: The World from the Twenties to the Eighties. New York: Harper and Row Publishers, 1983.
Not as fun or interesting to read as Geoffrey Perrett's book listed below, but full of more factual information.
.....
