For websites there are tools to save not only the URL but even interesting bits of pages. In PDF documents we can mark and often provide a link of interesting passages. But what do you do with old paper books when you come across something in them that you want to remember and/or be able to find? Then there is the handy Citez app. Allows you to take a photo of a page and then a crop of the passage. You can then link keywords to this. Title and author can look up the app itself by its isbn number, or you can enter them manually.
Citez is only available for iOS. Download it here.
Click the link above to download for free
Citez – Save Offline Texts