In addition to labeling your notes, you need to keep track of the sources of your notes.
You could write the full source on the back of each card or at the bottom of each chunk of text as you make a note, but that will get tiresome quickly.
Information Notecards and Master Notecards
Instead of rewriting the same publication information multiple times on your information notecards, try writing the full publication information of each source on one master notecard (or in one list). Then, in your notes or on the information notecards themselves, you only need to write the author and page number (for example, “Smith, p. 68”), and label it as a summary, paraphrase, or quote. The full publication information is already in your master set of references, so you don’t need to write all that down again.
When you are writing the draft of your paper, you may need to clarify an idea or find more information. Simply look at the correct notecard, and find the author and page number. Then, look at your master list or in your set of master notecards to find the full citation for the text. You now know exactly which book, article, or website you need to look at again. In addition, when the time comes to write out your References page in full for your final paper, you can just turn to your master list, and all your sources are right there.