Even though I declared it "Required Reading," maybe you're not up for a 500+ page graphic novel about a Japanese family's experience when their first child is diagnosed with autism. Maybe you just need some helpful strategies for the child who is in your classroom. Things you can do tomorrow.
In my experience, the best resources are the people who know the child well. Our school is lucky. We have experienced paraprofessionals who work with our special needs kids, with our special education teachers, and with regular education teachers throughout the elementary school career of the children. They are invaluable.
I asked our special ed teachers what professional books they would recommend for teachers of autistic children. Rather than books, they recommended Autism.com. The site is searchable -- try "teachers" or "teacher resources" for starters.
For further anecdotal reading, I would recommend Rules by Cynthia Lord, and Temple Grandin's work. (I found Temple Grandin by reading Oliver Sacks' fascinating books.)
Are there any other great (practical) resources you would recommend?