Exhibit D

                                   Exhibit D

                             JOINT FILING AGREEMENT

    In accordance with Rule 13d-1(k)(1) under the Securities Exchange Act of
1934, as amended, the persons named below agree to the joint filing on behalf of
each of them of the Schedule 13D (and any further amendment filed by them) with
respect to the common stock, par value $.001 per share, of ▇▇▇▇▇▇▇.▇▇▇, Inc.


                                                      
                                                       LL ACQUISITION CORP.

                                                       By:  /s/ ▇▇▇▇▇ ▇. ▇▇▇▇
                                                            -----------------------------------------
                                                            Name: ▇▇▇▇▇ ▇. ▇▇▇▇
                                                            Title:  Secretary

                                                       ASPEN PUBLISHERS, INC.

                                                       By:  /s/ ▇▇▇▇▇ ▇. ▇▇▇▇
                                                            -----------------------------------------
                                                            Name: ▇▇▇▇▇ ▇. ▇▇▇▇
                                                            Title:  Secretary

                                                       WOLTERS KLUWER U.S. CORPORATION

                                                       By:  /s/ ▇▇▇▇▇ ▇. ▇▇▇▇
                                                            -----------------------------------------
                                                            Name: ▇▇▇▇▇ ▇. ▇▇▇▇
                                                            Title:  Secretary

                                                       WOLTERS KLUWER NV

                                                       By:  /s/ ▇.▇.▇. ▇▇▇ ▇▇▇▇▇▇
                                                            -----------------------------------------
                                                            Name: ▇.▇.▇. ▇▇▇ ▇▇▇▇▇▇
                                                            Title:  Senior Vice President/
                                                                  Chief Financial Officer


Dated: December 29, 2000