Al Kowarizmi's algebra:
Al Kowarizmi was a very famous Arabic mathematician that wrote a book of mathematics. This book contains all of the principles of the algebra that we use nowadays. It also includes the whole concept of algorithm which is a corruption of Al Kowarizmi’s name.
Fibonacci's Liber Abaci:
This is Leonardo De Pisa’s most renown book. It talks about algebra and the arabic number system which we all use today. It’s basically the book that brought algebra, arithmetic and the arabic number system to Europe. It also talks about some of his most important discoveries and theorems such as the fibonacci sequence.