Hart Coal Company. In matter of Hart Coal Company and Hart Coal Corporation and United Mine Workers of America, District No. 23, affiliated with C. I. O. and Progressive Mine Workers of America, District No. 5, affiliated with A. F. of L., party to contract; in matter of [same] and United Mine Workers of America, District No. 23, affiliated with C. I. O., cases nos. C-1412 and R-1607; supplemental decision and certification of representatives, Apr. 25, 1940.