@bookSchryen_2007, title=Preventing E-mail Spam: The Conceptualization and the Analysis of an Infrastructure Framework, author=Schryen, Guido, year=2007 

@articleSchryen_2007, title=The Impact that Placing Email Addresses on the Internet has on the Receipt of Spamf? An Empirical Analysis, volume=2, number=5, journal=Computers &; Security, publisher=Elsevier, author=Schryen, Guido, year=2007, pages=361–372