https://archive.org/details/augustinus-der-zwiespalt-dr.-phil.-mathias-jung
https://archive.org/details/reizuberflutung-und-hochstleistungen-des-gehirns-arte
https://archive.org/details/the-simply-space-ist-der-stern-betelgeuse-eine-gefahr-fur-die-erde
https://archive.org/details/the-simply-space-hat-die-erde-einen-zweiten-geheimen-mond