Please refer to the following articles
C. J. Liu and Y. Chow. Enumeration of Connected Spanning Subgraphs Of A Planar Graph. Acta Mathematica Hungarica, 41(3):27–36, 1983.
C. J. Liu and Yutze Chow. On Operator And Formal Sum Methods For Graph Enumeration Problems. SIAM Journal of Control and Optimization, 5(3):384–406, 1984.
Y. Chow. On enumeration of spanning subgraphs with a preassigned cyclomatic number in a graph. Acta Mathematica Hungarica, 60(1):81–91, 1992.
C. J. Liu and Yutze Chow. Enumeration of forests in a graph. Proceeding of American Mathematical Society, 83(3):659–662, 1981.
