What disclaimer to be used to avoid copyright infringement issues while publishing a book summary on web?
A summary generally wouldn't require any kind of disclaimer. As long as you're not quoting heavily from the original material, you wouldn't be even close to infringing.If you are quoting heavily, the only disclaimer that might help would be one saying that you are quoting by permission of the copyright holder. But that will only help if you really dohave the permission of the copyright holder.