The two Dutch secret agents, Pieter Dourlein and Johan “Ben” Ubbink, who were the first SOE agents to escape from the prison at Haaren, were assisted by the Smit-van der Heijden line to cross into Belgium.
- Cookridge, E.H., Inside S.O.E., The First Full Story of Special Operations Executive in Western Europe, 1940-1945, London: Arthur Barker Ltd., 1966.
- Dourlein, Pieter, Inside North Pole: A Secret Agent’s Story, London: William Kimber, 1953.
- Giskes, H.J., London Calling North Pole, NY: Time-Life Books, 1990. For more on this, see http://spyinggame.me/2011/03/16/london-calling-north-pole-by-h-j-giskes-1953/.
- Kelso, Nicholas, Errors of Judgment, SOE’s Disaster in the Netherlands, 1941-44, London: Robert Hale, 1988.
- Marks, Leo, Between Silk and Cyanide, A Codemaker’s War, 1941-1945, New York: Touchstone Book, 2000.
- Van der Veer, Willem, De Koninklijke Marechaussee-Agenten en Het England-Spiel, Buren: Marechaussee Museum, 1993. (Brief accounts of the marechaussees who were among the Englandspiel agents who were killed.)
- Visser, Frank, De Schakel, Baarn, The Netherlands: Forum Boekerij, Ad.M.C. Stok, 1976.
- Wolters, Jo, Dossier Nordpol, Het Englandspiel Onder de Loep, Amsterdam: Boom, 2003. (Has an English language summary at the end.)
- For additional information on Englandspiel, see the website Englandspiel by Adri Wijnen: http://www.englandspiel.eu . For English speakers, when you connect to that website, click on “English” in the column to the left.
WWII Netherlands Escape Lines 
Dad was hillcat in belgium. Am interested in this because of proceedures explainef in his book
Dear Mr. Doneux,
I am unclear what you want me to do. You mention a book. What book? What is a hillcat?
Best wishes, Bruce Bolinger
Hillcat was capt jscques doneux t section soe