Numerical Study of the Wheatley-Hsu-Anderson Interlayer Tunneling   mechanism of High $T_c$ Superconductivity
  We present results obtained (by exact diagonalization) for the problem of two t-J planes with an interlayer coupling $t_\perp$. Our results for small hole concentrations show that in-plane superconducting correlations are enhanced by $t_\perp$. When the constraint on double occupancy in the t-J model is relaxed, the enhancement disappears. These results illustrate the inter--layer tunneling mechanism for superconductivity. 
M. Arjunwadkar, G. Baskaran, R. Basu and V. N. Muthukumar