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Manuzoid - Repository that includes user manuals for various products
Manuals Online - Manuals and free owners instruction pdf guides. Find the user manual and the help you need for the products you own at ManualsOnline.
Manula - Manula is an online software for creating user manuals.
ESI - ESI is a huge database containing equipment schematics, service manuals, and electronic components that you can explore online.
Dozuki - Dozuki is a web-based tool for creating and distributing step-by-step documentation.