BY ROBERT EIDELBERG IN HIS UNIQUE SERIES OF INTERACTIVE BOOKS ON KNOWING AND THINKING

WE DON'T KNOW: The Book of Non-Knowledge and the Volume of Our Current Ignorance

GOOD THINKING: A Self-Improvement Approach to Getting Your Mind to Go from "Huh?" to "Hmm" to "Aha!"

PLAYING DETECTIVE: A Self-Improvement Approach to Becoming a More Mindful Thinker, Reader, and Writer by Solving Mysteries

EVIDENTLY, MY DEAR ARMCHAIR DETECTIVE: Solving Ten Classic Mysteries Together With Their Celebrated Sleuths

"WHO'S THERE?" in Shakespeare's Hamlet - That Is the Question!