Note 6 - Property and Equipment (Details Textual) - USD ($)
|3 Months Ended|
Mar. 31, 2019
Mar. 31, 2018
|Depreciation, Total||$ 193,805||$ 264,353|
The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.
Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef