@misc{markert_natural_background_1991, 
author={Markert, B.,Zhang, D. L.},
title={Natural background concentrations of lanthanides in a forest ecosystem},
year={1991},
howpublished = {journal article},
note = {Online available at: \url{} (DOI). Markert, B.; Zhang, D.: Natural background concentrations of lanthanides in a forest ecosystem. Science of the Total Environment. 1991. vol. 103, 27-35.}}