First, to NYU's full page for the ad campaign, featuring all of the adverts in the campaign. Secondly, to the Autism Self Advocacy Network's open letter to NYU asking them to withdraw the campaign. You can also add your name to the list of signatories. It's a good letter, not too condemnatory, here's a short part to give you an idea of the tone:

In the press release announcing this campaign, the Center gave as one of its goals "eliminating the stigma of being or having a child with a psychiatric disorder". We are in full agreement with the goal of eliminating stigma against people with disabilities and their families. Yet, this campaign serves to increase that stigma rather than lessen it. We hope that you will heed our concerns and those of many other people with disabilities, family members, professionals, and countless others and end the "Ransom Notes" advertising campaign.