active mines in Yemen
... that in 2013, there were 819 active mines in Yemen producing stone, gypsum, refined petroleum products, and salt?
... that in 2013, there were 819 <b id="mwCv8"><a href="./Mining_industry_of_Yemen" id="mwCwA" rel="mw:WikiLink" title="Mining industry of Yemen">active mines in Yemen</a></b> producing stone, gypsum, refined petroleum products, and salt?