Now I am starting to learn Quantum Mechanics. In the class I am taught about operators, postulates and all other basic stuff. I understand operators to be +, -, /, etc; but quantum mechanical operators are entirely different; to understand them, I think, I need to know the historical development of the physics operators. So, I want to know how these operators were discovered/invented; some of the historical figures on this subject would also help along with some first text books from the original authors (modern texts are also okay). Thank you.