0001104659-04-009487 Sample Contracts

Exhibit A

Amendment to Schedule 13d • April 6th, 2004 • Oak Management Corp • Services-prepackaged software

• Contract Type
  Amendment to Schedule 13d
• Filed
  April 6th, 2004
• Company
  Oak Management Corp
• Industry
  Services-prepackaged software

Each of the undersigned hereby agrees that the Amendment No. 1 to Schedule 13D filed on the date hereof with respect to the shares of Common Stock of Cogent Communications Group, Inc. has been filed on behalf of the undersigned.