The best documentation is that of Google. Check out all of their docs<https://developers.google.com/web-toolkit/overview>. Read them all and you'll be an expert.
Sincerely, Joseph -- You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To view this discussion on the web visit https://groups.google.com/d/msg/google-web-toolkit/-/_CnwtNBi_cgJ. To post to this group, send email to google-web-toolkit@googlegroups.com. To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.