Fourier Series and Orthogonal Functions (Dover Books on Mathematics) by Harry F,

Modern Calculus and Analytic Geometry (Dover Books on Mathematics) VG

Calculus Refresher (Dover Books on Mathematics)

Calculus of Variations (Dover Books on Mathematics)

Modern Calculus and Analytic Geometry (Dover Books on Mathematics)

Fourier Series and Orthogonal Functions (Dover Books on Mathematics)

Essential Calculus with Applications (Dover Books on Mathematics)

Vector Calculus (Dover Books on Mathematics)