@misc{stuhrmann_methods_of_1989, 
author={Stuhrmann, H. B.},
title={Methods of isotopic and spin contrast variation in biology},
year={1989},
howpublished = {journal article},
note = {Online available at: \url{} (DOI). Stuhrmann, H.: Methods of isotopic and spin contrast variation in biology. Physica  B. 1989. vol. 156-157, 444-451.}}