ISBN: Unique identifing number for books. Stands for International Standard Book Number.
DOI: unique identifying code for journal articles. Stands for Digital Object Identifier.
WorldCat: a centralized website of library books including the authors, title, publication data and more. A "Library" of library data.
Picker: Intermediate and advanced programs have utilities to gather, or "pick", the data you need for citations straight from webpages.
The "Advanced" citation management programs build upon the features found in the other basic and intermediate programs, but have features that make not for the quick and easy research paper. Many of the features will not be needed in your first or second year papers, but they allow you to organize your research and organize your notes into your rough draft.
While not for the faint of heart, they have features that will make many students and professional researchers swoon.
Citavi is latin for "I cited." It was created in 1995 at the University of Dusseldorf in Germany where it gained wide support. In February 2011, an English version of the program was released. Citavi was buit BY academics and FOR academics. It combines many of the features of Zotero and Mendeley with easy document management and automated retrieval, but it also adds the ability to save quotes from your articles and organize your notes for your paper.
Citavi is a desktop program only available in Windows. You can use it on a Macintosh, however only when you run a virtualized Windows desktop - sadly, they had to abandon their plans to make a Mac version. Once you have downloaded the program, you can install a Citavi "picker" for Chrome, Firefox or Internet Explorer, which lets you download the information on the page for your references. It can also save the webpage as a PDF and add it to your research. Web pages, article DOIs, and book ISBNs are all easily added to any research project.
This video gives you all of the basics of Citavi in 3 minutes.