Note 6 - Income Taxes - Reconciliation of Income Tax Provisions (Details) - USD ($)	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Tax expense at U.S. Statutory rate	$ 2,990,768	$ 3,633,400
State income taxes, net of Federal benefit	88,909	77,989
Research and development credits	(86,223)	(126,320)
Foreign-derived intangible income deduction	(450,912)	(540,265)
Other	4,826	(269,543)
Income tax provision	$ 2,547,368	$ 2,775,261