Note 4 - Accounts Receivable, Net - Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accounts receivable	$ 4,867	$ 6,654
Allowance for doubtful accounts	(2,198)	(4,247)
Accounts receivable, net	$ 2,669	$ 2,407

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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