\Bibitem{Aki50} \by M.~A.~Akivis \paper Pairs of~$T$ complexes \jour Sb. Math. \yr 1950 \vol 69 \issue 3 \mathnet{http://mi.mathnet.ru/eng/sm5925} \mathscinet{https://mathscinet.ams.org/mathscinet-getitem?mr=42763} \zmath{https://zbmath.org/?q=an:0038.34005}