Cash and Cash Equivalents (Details) - USD ($)	Nov. 30, 2016	May 31, 2016	Nov. 30, 2015	May 31, 2015
Summary of cash and cash equivalents
Cash in banks	$ 4,134,320	$ 3,974,007
Money market funds	562,745	540,150
Total	$ 4,697,065	$ 4,514,157	$ 4,680,227	$ 3,669,790