A Course of Pure Mathematics is a classic textbook in introductory mathematical analysis, written by G. H. Hardy. 
It is recommended for people studying calculus. 

I. REAL VARIABLES
II. FUNCTIONS OF REAL VARIABLES
III COMPLEX NUMBERS
IV LIMITS OF FUNCTIONS OF A POSITIVE INTEGRAL VARIABLE
V LIMITS OF FUNCTIONS OF A CONTINUOUS VARIABLE. CONTINUOUS AND DISCONTINUOUS FUNCTIONS
VI DERIVATIVES AND INTEGRALS
VII ADDITIONAL THEOREMS IN THE DIFFERENTIAL AND INTEGRAL CALCULUS
VIII THE CONVERGENCE OF INFINITE SERIES AND INFINITE INTEGRALS
IX THE LOGARITHMIC, EXPONENTIAL AND CIRCULAR FUNCTIONS OF A REAL VARIABLE
X THE GENERAL THEORY OF THE LOGARITHMIC, EXPONENTIAL AND CIRCULAR FUNCTIONS