https://archive.org/details/geschichtsfenster-volksglauben-im-mittelalter
https://archive.org/details/dein-neues-mindset-ich-bin-absolut-gesund
https://archive.org/details/fermi-paradoxon-intelligentes-leben-im-universum-bruno-deiss
https://archive.org/details/europa-kontinent-im-umbruch-arte
https://archive.org/details/thesen-gegen-die-tote-zeit-der-naturwissenschaft-jochen-kirchhoff