No. 76-1878. Submitted May 18, 1977. Decided June 23, 1977. Allison W. Brown, Jr., Atty., N.L.R.B., Elliott Moore, Deputy Associate Gen. Counsel, and Frank Phillips, Atty., N.L.R.B., Washington, D.C., for petitioner; John S. Irving, Jr., Gen. Counsel, John E. Higgins, Jr., Deputy Gen. Counsel, N.L.R.B., Washington, D.C., on brief. Gale E. Fisher, May, Johnson Burke, Sioux Falls, S. D., for respondent; John E. Burke and Gale E. Fisher, Sioux Falls, S. D., on brief. Before VAN OOSTERHOUT, Senior Circuit