Windows Form Data Validation
http://www.codeproject.com/KB/validation/validationprovider.aspx (Great: Validators for Windows Forms - ValidationProvider Control , Score: 4.4/5)
(English)
Custom Windows Forms Validation (Updated 16 July, 2004): Custom validation component library for Windows Forms (English)
http://msdn.microsoft.com/en-us/library/ms951078.aspx (English)
http://www.mohundro.com/blog/CommentView,guid,d7356ed0-f604-465f-86f6-8c001c503865.aspx (English)
http://msdn.microsoft.com/en-us/library/ms229603.aspx (English)
http://www.codeproject.com/KB/validation/Validator.aspx (Bad: It is web validator, not winform validator, Validate user input in Windows Forms)
