It does have indexing, which I frequently use. If your pdf book does not have it, there's some readers who can add it. e.g. https://helpx.adobe.com/acrobat/usi

It does have indexing, which I frequently use. If your pdf book does not have it, there's some readers who can add it. e.g. https://helpx.adobe.com/acrobat/using/creating-pdf-indexes.html https://helpx.adobe.com/acrobat/using/creating-pdf-indexes.h...