- Sources:
- awk One-Liners By Eric Pement
- sed & awk, 2nd Edition, by Dale Dougherty and Arnold Robbins O'Reilly, 1997
- UNIX Text Processing, by Dale Dougherty and Tim O'Reilly Hayden Books, 1987
- Effective awk Programming, 3rd Edition. by Arnold Robbins O'Reilly, 2001