Here's another foundational paper: Hewitt, Carl; Bishop, Peter; Steiger, Richard (1973). "A Universal Modular Actor Formalism for Artificial Intelligence". IJC

Here's another foundational paper: Hewitt, Carl; Bishop, Peter; Steiger, Richard (1973). "A Universal Modular Actor Formalism for Artificial Intelligence". IJCAI. https://www.ijcai.org/Proceedings/73/Papers/027B.pdf https://www.ijcai.org/Proceedings/73/Papers/027B.pdf