Note 10 - Common Stock (Tables)

3 Months Ended

Mar. 31, 2020

Notes Tables

Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

	Exercisable	Expiration	Exercise		Under
Issuance Date	for	Date	Price		Warrants
February 2015	Common Shares	February 17, 2025	$	400.00		754
March 2015	Common Shares	March 26, 2025	$	272.00		14
May 2015	Common Shares	May 12, 2025	$	424.00		362
May 2015	Common Shares	May 17, 2020	$	424.00		215
December 2015	Common Shares	December 16, 2025	$	560.00		267
April 2016	Common Shares	April 1, 2026	$	608.00		250
May 2016	Common Shares	May 11, 2021	$	774.00		50
June 2016	Common Shares	June 20, 2026	$	498.00		1,004
May 2017	Common Shares	May 25, 2027	$	950.00		2,220
November 2019	Common Shares	November 26, 2020	$	1.55		6,393,113
November 2019	Common Shares	November 26, 2024	$	1.55		7,373,880
November 2019	Common Shares	November 26, 2024	$	1.84		9,893,776
						23,665,905