Beginning with SAS 9.0, the Excel LIBNAME engine can be used to assign a libref directly to Excel workbook files. 

Once the libref is assigned, the SAS Explorer window will display Worksheet names with a trailing dollar sign ($), while named ranged are displayed without the dollar sign. 

To reference the Excel Worksheet name in your SAS code, you must use the name literal syntax because worksheet names often contain special characters which are not valid as a standard SAS name. A name literal is specified with the worksheet name enclosed in single quotes and appending the letter n.

For example:

libname mylib "C:\My Documents\MyFile.xls";

proc print data=mylib.'Sheet1$'n;
run;

data sasuser.new;
   set mylib.'Sheet3$'n;
run;