1. Cho, I.: Graph Groupoids and Partial Isometries. LAP Publisher. ISBN: 978-3-8383-1397-9 (2009)
2. Cho, I.: $$K$$ -Theory on Groupoid Algebras Induced by Graphs (2011, preprint)
3. Cho, I.: Operations on Graphs, Groupoids, and Operator Algebras. LAP Publisher. ISBN: 978-8383-5271-8 (2010)
4. Cho, I.: Operator algebraic quotient structures induced by directed graphs. Comp. Anal. Oper. Theo. doi: 10.1063/1.3056588 (2010)
5. Cho, I.: Index on von Neumann algebras induced by graphs. Appl. Math. Sci. (2012, to appear)