1. B. Alspach, Searching and sweeping graphs: A brief survey, Le Matematiche, 34 pp
2. Arc searching digraphs without jumping;Alspach,2007
3. Directed path-width and monotonicity in digraph searching;Barat;Graphs and Combinatorics,2006
4. Searching is not jumping;Barrière,2003
5. Monotonicity in graph searching;Bienstock;Journal of Algorithms,1991