• Glicksman et al.
have measured the deviation S - P eP E1(P)
• LaCombe et al.
have also measured the shape deviation [1995].
• Horvay & Cahn [1961] found an exact needle crystal solution
with 2-fold
symmetry, exhibiting an amplitude-dependent deviation in S - P eP E1(P) [but wrong sign to account for 4-fold data …]