Scholastic
Scholastic Authors & Books: Paul Zindel's Biography
Scholastic's biography of Paul Zindel contains the author's memories of his early life, career choices, and reasons for writing: "I have to tell stories because that's the way the wiring went in."
Penguin Publishing
Penguin Random House: "The Gadget" Teacher Guide
"The Gadget" teacher guide features brief synopsis and list of themes as well as ideas for interdisciplinary connections.
Other
Charlotte Zolotow: Paul Zindel Becomes an Author
Editor Charlotte Zolotow's large site offers this page about Paul Zindel, how they met, and how she influenced his creative life. Especially interesting is Zindel's description of all she brought to his life and craft as a writer.