On estimating similarity of artificial and real organisms. - Maciej Komosinski; Grzegorz Koczyk; Marek Kubiak (Theory Biosci., 2001)

Domain Hierarchy and closed Loops (DHcL): a server for exploring hierarchy of protein domain structure. - Grzegorz Koczyk; Igor N. Berezovsky (Nucleic Acids Res., 2008)