The cohomology ring of certain families of periodic virtually cyclic   groups
  Let G be a virtually cyclic of the form (Z_a x Z_b) x Z or [Z_a x (Z b x Q_{2^i})] x Z. We compute the integral cohomology ring of G, and then obtain the periodicity of the Farell cohomology of these groups. 
S\'ergio Tadao Martins, Daciberg Lima Gon\c{c}alves and M\'arcio de   Jesus Soares
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