Exhibit 99.1
                                  ------------

         Pursuant  to  Rule  13d-1(f)(1)(iii)  of the  Securities  and  Exchange
Commission  under the Securities  Exchange Act of 1934, as amended,  each of the
undersigned agrees that the statement to which this Exhibit is attached is filed
on its behalf.


September 25, 1997                     SEGI HOLDING COMPANY


                                       By:   \S\  Michael D. Fricklas
                                             -----------------------------------
                                             Name:   Michael D. Fricklas
                                             Title:  Senior Vice President,
                                                     Deputy General Counsel



                                       VIACOM INC.


                                       By:   \S\  Michael D. Fricklas
                                             -----------------------------------
                                             Name:  Michael D. Fricklas
                                             Title: Senior Vice President,
                                                    Deputy General Counsel





                                       By:               *
                                             -----------------------------------
                                             Sumner M. Redstone, Individually



*By: \S\  Philippe P. Dauman
     ---------------------------
     Philippe P. Dauman
     Attorney-in-Fact under the
     Limited Power of Attorney
     filed as Exhibit 99.2 to the
     Statement, Amendment No. 11