Regex find at least one of two characters

Regex find at least one of two characters

References

Reference NO 1

http://www.regular-expressions.info/reference.html

Reference NO 2

http://stackoverflow.com/questions/15200835/regex-find-at-least-one-of-two-characters

Reference NO 3

http://www.dreambank.net/regex.html

Reference NO 4

http://www.gnu.org/software/sed/manual/html_node/Regular-Expressions.html

Reference NO 5

http://gravity.tbates.org/reg-101.html

Reference NO 6

http://publib.boulder.ibm.com/infocenter/zvm/v5r4/topic/com.ibm.zvm.v54.dmsp3/regexpa.htm

Reference NO 7

http://msdn.microsoft.com/en-us/library/3206d374.aspx

Reference NO 8

http://www.ruby-doc.org/core-1.9.3/Regexp.html