\Bibitem{LycRub89} \by V.~V.~Lychagin, V.~N.~Rubtsov \paper Topological indices of spencer complexes associated with geometric structures \jour Mat. Zametki \yr 1989 \vol 45 \issue 4 \pages 59--68 \mathnet{http://mi.mathnet.ru/mzm3471} \mathscinet{http://mathscinet.ams.org/mathscinet-getitem?mr=1002135} \zmath{https://zbmath.org/?q=an:0697.58049} \transl \jour Math. Notes \yr 1989 \vol 45 \issue 4 \pages 305--312 \crossref{https://doi.org/10.1007/BF01158892} \isi{https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=Publons&SrcAuth=Publons_CEL&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=A1989CH91000021}