Branching Principal Components: Elastic Graphs, Topological Grammars and Metro Maps. - Alexander N. Gorban; Neil R. Sumner; Andrei Yu. Zinovyev (IJCNN, 2007)

Topological grammars for data approximation. - Alexander N. Gorban; Neil R. Sumner; Andrei Yu. Zinovyev (Appl. Math. Lett., 2007)