The following references were accessed by the author on April 22, 2014:
Linux Manual Pages at http://www.tldp.org/manpages/man.html
Linux man pages online http://man7.org/linux/man-pages/index.html
15 Practical Grep Command Examples at http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/
Examples using grep at http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_04_02.html
Regular expressions at http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_04_01.html
Linux Programmer's Manual, Man 1 intro at http://www.man7.org/linux/man-pages/man1/intro.1.html
Linux Programmer's Manual, Man 2 intro at http://www.man7.org/linux/man-pages/man1/intro.2.html