No. 78-1117. Submitted August 9, 1978. Decided November 7, 1978. Glen A. Bergmann, Denver, Colo., for petitioner. Allison W. Brown, Jr. and Peter Winkler, N.L.R.B., Washington, D.C., for respondent. Petition from the National Labor Relations Board. Before BARRETT, DOYLE and McKAY, Circuit Judges. McKAY, Circuit Judge. This case involves a petition for review of a National Labor Relations Board (NLRB) order and the NLRB's cross-application for enforcement of that order. We must sustain the NLRB's