Just click on the link below to download mathematics books.
Following books of mathematics are in djvu file format, to read this book u have to download djvu reader so i give u one link to download djvu reader. if u got any problem then comment here.
Discrete Mathematics :
AdvancedEngineeringMaths-Kreyzig
ROSEN
Discrete mathematics and it's applications 6th Edition
Graph.Theory Narisng Deo
Schaum's Outline of Differential Equations
Differential calculus schaum series
Schaum outline DiscretMath
DJVU reader....
............................Best of Luck.