WinForms Custom Controls

https://www.codeproject.com/Articles/5015/Validating-Edit-Controls

https://www.codeproject.com/Articles/1425/Validating-Edit-Controls

https://www.codeproject.com/Articles/806/A-Validating-Edit-Control

User Input Validation in Windows Forms

https://docs.microsoft.com/en-us/dotnet/framework/winforms/user-input-validation-in-windows-forms

Extending Windows Forms with a Custom Validation Component Library

https://msdn.microsoft.com/en-us/library/ms950965.aspx

Extend the Textbox Control to Validate Against Regular Expressions

https://www.c-sharpcorner.com/article/extend-the-textbox-control-to-validate-against-regular-expressions/

https://www.codeproject.com/Articles/13922/Validate-user-input-in-Windows-Forms

https://www.codeproject.com/Articles/10093/Validators-for-Windows-Forms-ValidationProvider-Co

http://blog.scosby.com/post/2010/02/11/Validation-in-Windows-Forms.aspx

Source code

https://github.com/IgnaceMaes/MaterialSkin

Some Controls written in C# inherit from TextBox

https://github.com/smx-smx/open-sauce

Bài toán của phần mềm kế toán

https://xceed.com/xceed-input-validator-for-winforms/