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STOCKHOLDERS' EQUITY - STOCK-BASED COMPENSATION TO SERVICE PROVIDERS (Details) - USD ($) | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Stock-Based Compensation to Service Providers |  |  |
Stock-based compensation for services by non-employees | $ 68,000 | $ 191,000 | $ 200,000
Consultants | Stock Options |  |  |
Stock-Based Compensation to Service Providers |  |  |
Stock-based compensation for services by non-employees | $ 24,000 | $ 50,000 | $ 41,000

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