1)External Sorting: Example of Two-Way Sorting:
http://faculty.simpson.edu/lydia.sinapova/www/cmsc250/LN250_Weiss/L17-ExternalSortEX1.htm

2)External Sorting: Example of multiway external sorting
http://faculty.simpson.edu/lydia.sinapova/www/cmsc250/LN250_Weiss/L17-ExternalSortEX2.htm