Here are some good resources about QR codes.
Wikipedia - QR Code Detailed coverage of standards, usage, design, etc.
- How to Use QR Codes in Your Print Marketing Advice about when and how to use QR codes. From July 2013.
- QR Codes for Marketing: A Unique Way to Bridge Offline and Online Media Usage and examples of QR codes. From Nov 2010.
- 5 Genius Examples of QR Codes in Marketing Examples of creative QR code usage. From January, 2012.
- How to Use QR Codes in Your Marketing Campaign Tips about implementing QR codes. From April 2014.
- Capture Mobile Consumers with QR Codes on your Print Material Advice from a print shop. From March 2013.