May 1981, “Wiggler and undulator magnets” by Herman Winick, George Brown, Klaus Halbach and John Harris appeared with the following misprints: page 52, caption of figure 3 should read “with polarization parallel (σ).” page 54, legend of figure 6 for black curves should read “(in operation)” instead of “(under construction).” page 56, caption of figure 7 should read “Program by Y. Zambre.” page 57, first column “〈B〉2” should read “〈B2〉” caption of figure 8, should read “(typically 2 microns).” page 58, third column, fourth line, should read “The undulator radiation retains the intrinsic brightness of synchrotron radiation because …” first figure in box revised as follows: (see PDF for diagram) page 60, first column, starting 14 lines from bottom should read “the transverse beam size (σx,σy) should satisfy the condition σ/L<γ−1N−1/2, where L is the distance from the undulator to the detector; the electron beam divergence angles (σx′,σy′) should satisfy σ′<γ−1N−1/2.” page 62, equation 8 should read B0=2Br exp(−πg/λu)×sinπ/Mπ/M[1−exp(2πh/λu)] middle column, line end of first paragraph should read “…from 3–7 keV are shown in figure 9”. May 1981, “Facilities in the United States” by Ednor M. Rowe: table, page 36, “A. I. Bienstock” should read “A. I. Bienenstock”; “Standford, CT” should read “Stanford, CA.”