1. Adámek, J., Rosický, J., Vitale, E.M.: Algebraic theories. In: Cambridge Tracts in Mathematics, vol. 184. Cambridge University Press, Cambridge. A categorical introduction to general algebra. With a foreword by F. W. Lawvere (2011)
2. Baues, H.J.: Quadratic functors and metastable homotopy. J. Pure Appl. Algebra 91(1–3), 49–107 (1994)
3. Baues, H.J.: Homotopy type and homology. In: Oxford Mathematical Monographs. The Clarendon Press, New York (1996)
4. Baues, H.J.: Derived functors of graded theories. K-Theory 17(2), 151–193 (1999)
5. Baues, H.J., Goerss, P.: A homotopy operation spectral sequence for the computation of homotopy groups. Topology 39(1), 161–192 (2000)