Math

Angular Momentum

NIST Digital Library of Mathematical Functions, 3j, 6j, 9j symbols

Wolfram, 3-j symbols page

Varshalovich, Moskalev & Khersonskii, Angular Momentum in Quantum Mechanics

Louck, Theory of Angular Momentum in N-Dimensional Space

Rose, Elementary Theory of Angular Momentum

Edmonds, Angular Momentum in Quantum Mechanics

Spherical Harmonics, Legendre Polynomials, and the Plane Wave Expansion

Wikipedia, Table of Spherical Harmonics (including Cartesian form)

Wolfram, Spherical Harmonics page

Wolfram, Spherical Harmonic Addition Theorem page

Wolfram, Legendre Polynomials page

Wolfram Demonstrations, Spherical Harmonics (real form)

Wolfram Demonstrations, Complex Spherical Harmonics (what we typically use)

Spherical Bessel Functions

NIST DLMF, Bessel Functions

Watson 1922, A Treatise on the Theory of Bessel Functions

David Tong lecture notes on Spherical Bessel Functions

Hitoshi Murayama notes on Spherical Bessel Functions

1988 review on numerical methods for calculating SBFs

Special Functions

NIST DLMF, Hypergeometric Functions

Pearson, Master's Thesis on Computation of Hypergeometric Functions

Snow, Hypergeometric and Legendre Functions With Applications to Integral Equations of Potential Theory

Erdelyi (Bateman Manuscript Project), Higher Transcendental Functions, vol. 1

Ibid, vol. 2

Ibid, vol. 3

Integrals

Gradshteyn & Ryzhik, Table of Integrals, Series, and Products (7th ed.)

Ng & Geller 1968, A Table of Integrals of the Error Functions 

Wolfram functions site, Hypergeometrics

Wolfram functions site, Meijer G

Complex Analysis/Contour Integrals

Hitoshi Murayama notes on contour integration

Calculus and Algebra Review

Tong, Lectures on Vector Calculus

Bleau, Forgotten Algebra

Triangles

Triangle properties, Wolfram page

Trigonometry

Basics, Wolfram page

Addition formulas, Wolfram page

Sum to product formulas, Wolfram page

Also: slightly different form here

Power formulas, Wolfram page

Circles/Ellipses

Circle, Wolfram page

Ellipse, Wolfram page

Tetrahedra

Tetrahedron, Wolfram page

Matrices

Matrix determinant, Wolfram page