Spring actuated ball projecting device
作者： Arthur L Saveca
DOI:
关键词: Structural engineering 、 Ball (bearing) 、 Geology
摘要:
lens.org 参考文章(3)
James K Pope, Air gun projectile holder ,(1947)
Albert E. Eccles, Maurice J. Hatfield, Game and game apparatus therefor ,(1936)
Skala Josef, Toy shooting device ,(1923)