CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($)	May 31, 2020	May 31, 2019
Allowance for doubtful accounts (in Dollars)	$ 70,981	$ 73,110
Common stock par value (in Dollars per share)	$ 0.08	$ 0.08
Common stock, shares authorized	25,000,000	25,000,000
Common stock, shares issued	11,740,089	9,677,188
Common stock, shares outstanding	11,740,089	9,677,188
5% Convertible Preferred Stock [Member] | Series A Preferred Stock [Member]
Preferred Stock, Par Value (in Dollars per share)	$ 0.08
Preferred Stock, shares authorized	571,429
Preferred Stock, shares issued	321,429
Preferred Stock, shares outstanding	321,429
Preferred Stock [Member]
Preferred Stock, shares issued	0	0
Preferred Stock, shares outstanding	0	0
Preferred Stock, No Par Value (in Dollars per share)	$ 0	$ 0
Preferred Stock, undesignated shares	4,428,571	5,000,000