<em>Heim, Arnold: Kalkstein im Grasland, 1961 (Dia_319-38, <a href="http://doi.org/10.3932/ethz-a-000891916">http://doi.org/10.3932/ethz-a-000891916</a>)
<em>Heim, Arnold: Kalkstein im Grasland, 1961 (Dia_319-38, <a href="http://doi.org/10.3932/ethz-a-000891916">http://doi.org/10.3932/ethz-a-000891916</a>)
