"Gustav Lilienthal (October 9, 1849 – February 1, 1933) was a German social reformer, a pioneer in building and construction technology (Prefabricated buildings), inventor of different ...
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Construction sets (e. g. Anchor Stone Blocks) and involved in the pioneering work of his brother, Otto Lilienthal in aviation." - (en.wikipedia.org 22.10.2019)