Britmovie - The 39 Steps: Cast information, trailer, and review.
Greatest Films: The Thirty-Nine Steps: Detailed review, synopsis and discussion of thematic elements in the film
IMDB : 39 Steps, The (1935): Full cast and crew for the film, and other information from the Internet Movie Database.
Scotland the Movie Location Guide - The 39 Steps: Scottish filming locations for The 39 Steps