Some valid sheeet names are as under among the other various names

t'#3cfbsdjfdsjb''''''''^^^^^^&&'!$C$8:$N$23   

1'!$E$13:$H$19    

!'!$B$7:$E$16    

@@@@@@@'!$B$7:$K$21

!$'!$B$12:$M$17

Iam using

string pattern =@"[^<]+?\!\$[A-Z]+\$[0-9]+"

Regex r = new Regex(Constants.CELL_REFERENCE_PATTERN);
            Match m = r.Match(selectedVal);
            if (m.Success) return true;
            else return false;

but it is failing for

"t'#3cfbsdjfdsjb''''''''^^^^^^&&'!$C$8:$N$23,p,mv" or "sheeet1!$A1."

Thanks in advance

Ignoring the C# factor, these are regular expressions that I have found to work.

Cell Reference with sheet optional (<sheet>!<cell>)

"(('[^/\\?*\[\]]{1,31}'|[A-Za-z0-9_]{1,31})!)?((\$?[A-Za-z]{1,3})(\$?[0-9]{1,6}))"

Notes:

• This regex does not validate Cell values, ex. ZZZ999999 is valid through the regex, but it is not a valid location inside of Excel.
• This is for Excel 2007+. For pre-2007, change {1,3} to {1,2} and {1,6} to {1,5}. This is because the range of cells went from IV65536 (pre-2007) to XFD1048576 (2007+). But of course, there is no validation and technically it could be [A-Za-z]+ and [0-9]+.