@book{ BA0790562X, author = "Hahn, Geňa and Sabidussi, Gert and Woodrow, Robert E. and NATO Advanced Research Workshop on Cycles and Rays: Basic Structures in Finite and Infinite Graphs and North Atlantic Treaty Organization. Scientific Affairs Division", title = "Cycles and rays", publisher = "Kluwer Academic Publishers", year = "1990", series = "NATO ASI series", number = "ser. C . Mathematical and physical sciences ; v. 301", URL = "https://ci.nii.ac.jp/ncid/BA0790562X" }