From publisher blurb: While the word zeppelin is often used to refer to any aircraft that relies on lighter than air gasses to stay aloft, but the terms was originally a brand name used by the Zeppelin Company. In modern it has become generalized to refer to all rigid airships, whose shapes are determined by a skeleton of aluminum tubes, as opposed to a non-rigid airship (blimps), which retain their shape due to internal air pressure. This 10 page PDF is an easy-to-integrate sourcebook and just the sort of thing needed for GMs to add depth to any great d20 Modern Neo-Pulp setting and campaign world including Haven: City of Bronze.