Author:
Shaykh Al-Fawzan
The excellent book of Sheikh Salih al-Fawzan Aqidah at-Tawhid. It includes all the basics to know in the field of belief and many very interesting information.  
( Side Note this book has a little water damage so the 10% is added to it we hope ان شاء الله this would be satisfying to our customers). Other copies are new