Darby, Gene.
What is a simple machine / Gene Darby ; illustrated by Robert W. Friedl. - Chicago : Benefic Press, c 1961. - 48 p. : ill. ; 20 cm. - The what is it series. .
318 318
Tools and fabricating equipment.
621.9 / D242w
What is a simple machine / Gene Darby ; illustrated by Robert W. Friedl. - Chicago : Benefic Press, c 1961. - 48 p. : ill. ; 20 cm. - The what is it series. .
318 318
Tools and fabricating equipment.
621.9 / D242w