Singer claims to have coined the term "neurodiversity" in her undergrad thesis about autism, disability and society, which is printed here with a lengthy Introduction. It's a quick read and a worthwhile one from a historical perspective and for its blend of social commentary, autism advocacy and personal memoir.
It's interesting to note that the term "neurodiversity" now covers a much bigger range than just the categories of neurotypicals and autistic people/Aspies. It's been adopted as an umbrella to cover dyslexia, dyscalculia, dyspraxia, AD(H)D, stroke survivors and more. It's become an important social movement in less than twenty years but still needs much greater recognition and acceptance by society as a whole.