21, Berlin 2009, ISBN 978-3643105493*Williams, Thomas D, (2011), "The World As It Could Be: Catholic Social Thought for a New Generation", ISBN 082452666X.
21, Berlin 2009, ISBN 978-3643105493* Williams, Thomas D, (2011), "The World As It Could Be: Catholic Social Thought for a New Generation", ISBN 082452666X.