Anharmonic temperature factors: the limitations of perturbation theory expressions. Erratum

The parts of Fig. 1 in Mackenzie & Mair [Acta Cryst. (1985). A41, 81-85] have been wrongly labelled, so that (a) to (d) and (e) to (h) run vertically. The correct labelling has parts (a) and (b) on the top line, (c) and (d) on the second line, (e) and (f) on the third line and (g) and (h) at the bottom. References to Scheringer (1984a, b) should read Scheringer (1985a, b).