The most foolproof method is to use CTRL-V (Mac: ⌘-V) to paste your references into the Input References box.

You can also right-click to paste, but because of the way browsers interact with the input field, you have to be a little bit more careful. Have you ever tried to paste your references by right-clicking and, instead of the expected Paste options, seen a menu that looks something like this?

You can resolve this issue by clicking right next to the cursor, like this:

You should then get this pop-up menu:

Happy pasting!