Göttingen Collection of Mathematical Models and Instruments

	(64) Developable helicoid		(65) Standard helicoid
	(66) Standard helicoid		(67) Standard helicoid
	(68) Developable helicoid		(70) Pipe helicoid with curve lines
	(71) Helical surface		(222) Surface of constant width
	(223) Surface of constant width		(224) Surface of constant width
	(229) Surface of constant width		(243) Helical surface
	(378) Helical surface		(379) Developable helicoid and cylinder through the edge of regression