Note 8 - Warrants

9 Months Ended

Sep. 30, 2019

Notes to Financial Statements

Warrants [Text Block]

8 . Warrants

At

September 30, 2019

and

December 31, 2018,

we had

3,963,505

and

4,080,005

warrants outstanding, respectively and exercisable with a weighted average exercise price of

$4.33

and

$4.35,

respectively. During the

three

and

nine

month period ended

September 30, 2019,

87,500

and

116,500

warrants were exercised with a weighted average exercise price of

$4.75,

yielding proceeds of

$416,000

and

$553,000,

respectively. The outstanding warrants have expiration dates between

March 2021

and

May 2021.