Spiess, Hans W. MPI for Polymer Research, Max Planck Society;
http://www.sciencedirect.com/science/article/pii/0301010474850627/pdf?md5=b7ff05dc53e4265a05dd4cc6af8acb17&pid=1-s2.0-0301010474850627-main.pdf (Any fulltext)
https://doi.org/10.1016/0301-0104(74)85062-7 (Any fulltext)
Spiess, H. W. (1974). Molecular motion studied by NMR powder spectra. I. Lineshape calculation for axially symmetric sheilding tensors. Chemical Physics, 6(2), 217-225. doi:10.1016/0301-0104(74)85062-7.