Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
Accounts receivable-trade, net allowance for doubtful accounts	$ 75	$ 1,746
Accumulated amortization	$ 707,750	$ 701,752
Preferred stock, par value (in dollars per share)	$ 0.10	$ 0.10
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0024	$ 0.0024
Common stock, shares authorized (in shares)	25,000,000	25,000,000
Common stock, shares issued (in shares)	11,309,326	11,275,641
Common stock, shares outstanding (in shares)	9,266,496	9,753,293
Treasury stock, shares (in shares)	2,042,830	1,522,348