A formula, recently discovered by Cyvin, relates the numbers of Kekul structures of unbranched catacondensed benzenoid molecules. It is shown that Cyvin's formula is a special case of a much more general result. The determinants occurring in Cyvin's formula as well as in our generalized version thereof can be interpreted in terms of correlation functions for die choices of pairs of double or pairs of single bonds in the Kekul structures of the respective conjugated system. 1991 J.C. Baltzer A.G., Scientific Publishing Company.
