A perturbed γγ angular correlation study of 111In, implanted into a suitably cut single crystal, showed that the stacking fault was not a planar faulted loop but was a stacking-fault tetrahedron with a size of 10 to 50Å.

On the Stacking Fault in Copper. J.R.Fransens, F.Pleiter: Hyperfine Interactions, 2003, 151-152[1-4], 155-71