I am reading this book on Scribd. How can I look for a keyword in this document?
The first portion of my answer has nothing to do with your question, but I thought I'd mention it as an FYI.
According to the support desk at Scribd ctrl + f is only supported if "the document's publisher has allowed copying/pasting from the document." This is a bug they are currently trying to resolve.
Your best bet is to go to "Edit" or "Tools" in your web browser's menu and click "Find" to search for a particular keyword.