CONDENSED CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($)	Feb. 29, 2020	May 31, 2019
Allowance for doubtful accounts (in Dollars)	$ 76,681	$ 73,110
Accumulated depreciation and amortization (in Dollars)	$ 1,688,685	$ 1,762,344
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	10,310,355	9,677,188
Common stock, shares outstanding	10,310,355	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	571,429
Preferred Stock, shares outstanding	571,429
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