Resources for learning the matrix formulation of quantum mechanics include Wikipedia's bra-ket notation and Caltech's lecture notes, specifically Chapter 2. In quantum mechanics, a vector in a finite-dimensional space is represented as a column vector, while the position space wavefunction can be viewed as a vector in an infinite-dimensional space. Understanding the differences between finite and infinite dimensions is crucial, but starting with finite dimensions can provide useful intuition. Operators acting on these states can be represented as matrices, with the Hamiltonian being a key example. Claude Cohen-Tannoudji's "Quantum Mechanics" is recommended for further study.