Wieland, Theodor Max Planck Institute for Medical Research, Max Planck Society;
http://onlinelibrary.wiley.com/doi/10.1002/anie.197507021/epdf (Any fulltext)
https://doi.org/10.1002/anie.197507021 (Any fulltext)
Siemion, I. Z., Wieland, T., & Pook, K.-H. (1975). Influence of the distance of the proline carbonyl from the β and γ carbon on the 13C chemical shifts. Angewandte Chemie International Edition, 14(10), 702-703. doi:10.1002/anie.197507021.