Nos. 90-3446 and 90-3543. Argued January 22, 1991. Decided July 17, 1991. Steven Semler (argued), Semler Pritzker, Washington, D.C., for petitioner at No. 90-3446 and respondent at No. 90-3543, North American Directory Corp. Peter Winkler, Joseph Oertel (argued), Jerry M. Hunter, Robert E. Allen, Aileen A. Armstrong, Robert F. Mace, N.L.R.B., Washington, D.C., for respondent at No. 90-3446 and Petitioner at 90-3543, N.L. R.B. Ira Weinstock (argued), Edward Gleason, Ira H. Weinstock, P.C., Harrisburg