The eminent mathematician of the 20th century, Paul Erdős, often mentioned "The Book" in which God keeps the most elegant proof of every mathematical theorem. So, when he attended mathematical talks, he would say: "This is a proof from The Book," or "This is a correct proof, but it’s not from The Book." M. Aigner and G. Ziegler authored the highly popular "Proofs from THE BOOK" (translated into 13 languages). Sergei Tabachnikov, professor at Penn State University, will present several proofs not included in the Aigner-Ziegler book, but, that in his opinion, could belong in it.