Consolidated Balance Sheets (Parentheticals) - USD ($)	Mar. 31, 2018	Mar. 31, 2017
Allowance for doubtful accounts	$ 35,000	$ 27,000
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, liquidation preference (in dollars per share)	$ 4	$ 4
Preferred stock, shares issued (in shares)	3,000	3,000
Preferred stock, shares outstanding (in shares)	3,000	3,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	40,000,000	40,000,000
Common stock, shares issued (in shares)	20,601,000	20,526,000
Common stock, shares outstanding (in shares)	20,601,000	20,526,000