References
Translation:
Books
Walther Pistols, by W.H.B. Smith. Stackpole, Harrisburg, Pennsylvania: 1946.
Walther Pistols: Models 1 Through P99, by Dieter H. Marschall. Ucross Books, Los Alamos, NM: 2000.
Walther, Volume 3 1908-1980, by James Rankin, Coral Gables, FL: 1981
H&L Publishing, Walther Model 4
Web Sites
Unblinking Eye Gun Pages: http://unblinkingeye.com/Guns/
Cruffler.com: http://www.cruffler.com/historic-march00.html
Vestpocket Pistol Collector: http://www.vestpockets.bauli.at/archiv/archiv.htm
CARL WALTHER GmbH: http://www.carl-walther.de/
Zella-Mehlis Proof House: http://www.beschussanstalt.zella-mehlis.de/en/?Welcome