Non-Universality in Semi-Directed Barabasi-Albert Networks
  In usual scale-free networks of Barabasi-Albert type, a newly added node selects randomly m neighbors from the already existing network nodes, proportionally to the number of links these had before. Then the number N(k) of nodes with k links each decays as 1/k^gamma where gamma=3 is universal, i.e. independent of m. Now we use a limited directedness in the construction of the network, as a result of which the exponent gamma decreases from 3 to 2 for increasing m. 
M.A. Sumour and M.A. Radwan
physics.comp-ph cs.SI physics.soc-ph