Note 4 - Revenue Recognition (Details Textual) - USD ($)	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Contract with Customer, Liability, Total	$ 427,193	$ 497,351	$ 859,370
Minimum [Member]
Contract with Customer, Liability, Remaining Performance Obligation, Expected Timing of Satisfaction, Period (Year)	1 year
Maximum [Member]
Contract with Customer, Liability, Remaining Performance Obligation, Expected Timing of Satisfaction, Period (Year)	3 years