Along with the Novels released in 2009, in the same year, Giunti Junior released as well two other books with informations about the characters, the story plot and the world of the humans and eternals.

Angel's Friends - Diario Segreto

AF diary

"Angel's Friends - Diario Segreto" Front Cover

Translated to English as "Angel's Friends - Secret Diary", this book reveals
AF diary 2

"Angel's Friends - Diario Segreto" Back Cover

the entries of Raf's secret diary as well as the world of the other characters but mainly focused on the story of Raf and Sulfus:

"A secret diary all for you!!! Raf, 99% angel, will guide and help you living every day as a fantastic fly of explanatory wings!"

This book is composed by 130 pages. The author of the book is unknown. 

Il Mondo di Angel's Friends

AF book 4

"Il Mondo di Angel's Friends" Front Cover

Translated to English as "The World of Angel's Friends", this book reveals
AF book 4 II

"Il Mondo di Angel's Friends" Back Cover

the profiles of the characters, the story plot, curiosities and also a special about Raf's and Sulfus' feelings for each other:

"Enter in the world of the Eternals, where Heaven and Hell challenge, fight and touch each other for the humanity's decisions!"

This book is composed by 132 pages. Rosalba Troiano, author of the Novels, is also the author of this book.