Note 2 - Significant Accounting Policies - Antidilutive Securities (Details) - shares	6 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Warrant [Member]
Antidilutive securities (in shares)	21,270,102	18,784,324
Share-based Payment Arrangement, Option [Member]
Antidilutive securities (in shares)	9,511,600	7,801,600
Convertible Debt Securities [Member]
Antidilutive securities (in shares)	11,215,175	9,779,000
Convertible Preferred Stock Antidilutive Securities [Member]
Antidilutive securities (in shares)	19,500	18,500

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration