Note 3 - Accounts Receivable, Net (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2016
Accounts receivable	$ 15,064,580	$ 15,267,962
Less: allowance for doubtful accounts	(658,104)	(567,108)	$ (567,108)	$ (670,280)
Accounts receivable, net	$ 14,406,476	$ 14,700,854

Amounts due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer) for goods or services (including trade receivables) that have been delivered or sold in the normal course of business.

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- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
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- Definition

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

+ References

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