sentences:  Owing to the provisions of the Versailles treaty, many of the planes were initially produced in Italy, Spain, the Netherlands or Japan, but resumed work at its Friedrichshafen and other German factories following the rise of the Nazi regime.The 1937 Hindenburg disaster and a subsequent embargo on sending American helium to Germany, however, effectively ended the production of German dirigibles.The Zeppelin manufacturing company Luftschiffbau Zeppelin (LZ) was re-established in 1993, and a commercial airline Deutsche Zeppelin Reederei (DZR) began flying passenger service from Friedrichshafen Airport in 2001. , 12 scheduled routes were offered with additional flights to selected cities.