Note 6 - Stockholders' Equity - Summary of Additional Information About Stock Options Outstanding and Exercisable (Details) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Options Outstanding (in shares)	101,500	85,000
Options Outstanding, Weighted Average Remaining Contractual Life (Year)	5 years 6 months 21 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 2.97	$ 2.52
Options Outstanding, Aggregate Intrinsic Value	$ 151,800
Options Exercisable (in shares)	76,500	32,500
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 3.15	$ 2.52
Options Exercisable, Aggregate Intrinsic Value	$ 104,500