Note 11 - Short-term Investment (Details Textual)	1 Months Ended	3 Months Ended		6 Months Ended	9 Months Ended
	Jun. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2020 HKD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 HKD ($)
Debt Securities, Held-to-maturity, Current	$ 516,121	$ 516,121		$ 512,821	$ 516,121		$ 4,000,000	$ 512,821	$ 4,000,000
Investment in Held-to-maturity Debt Securities, Term (Year)				1 year
Investment in Held-to-maturity Debt Securities, Interest Rate	5.00%			5.00%			5.00%		5.00%
Investment Income, Interest	$ 25,800	$ 1,106	$ 19		$ 26,908	$ 143
Limit of Bond							$ 20,000,000