NEW YORK--(BUSINESS WIRE)--Halper Sadeh LLC, an investor rights law firm, is investigating whether the sale of Gold Resource Corporation (NYSE American: GORO) to Goldgroup Mining Inc. for 1.4476 common shares of Goldgroup for each share of Gold Resource common stock is fair to Gold Resource shareholders. Halper Sadeh encourages Gold Resource shareholders to click here to learn more about their legal rights and options or contact Daniel Sadeh or Zachary Halper at (212) 763-0060 or sadeh@halpersadeh.com or z ...