by Ronald A. Howard and James E. Matheson
In this paper [$], Professor Ron Howard and Dr. Matheson define and develop the influence diagram. Also known as Bayesian Networks, the influence diagram has become one of the most widely used tools in the area of decision making and statistical inference. This paper presents the different node types, the meaning of differing arrows between nodes, and rules regarding their construction.
First published in 1981 in The Principles and Applications of Decision Analysis. Reprinted in 2005 in Decision Analysis. The first page is free and the complete paper is available for purchase at this link.