Before we even get to the idea of citation, let's make sure one thing is clear: if you are using a word-for-word, literal quotation, you have to put the passage you are quoting in quotation marks. If it is a long passage--more than three lines of text in your paper--you should start a new line and indent, putting the citation at the end of the paragraph. Only these two mechanisms are acceptable for indicating quoted material.
Believe it or not, if you leave out the quotation marks, you can be brought to an honor board. One of my students recently transferred a paper from Microsoft Works to WordPerfect. Somehow when he did this, all the quotation marks were stripped from the paper. I hesitate to think what might have happened had he turned in the paper without proofreading it. (Probably he could have shown the professor the earlier draft with the quotation marks and have explained what happened, but it still could have been a major hassle. Unfortunately the interpretation that he was deliberately trying to pass off someone else's work as his own would have had to have been considered.)
But I digress. There are several systems for citing, or giving reference to, the ideas of others. Some professors want you to use a specific system. Others don't care which you use, as long as you are consistent. All professors want you to present complete information. For example, if you are citing the Heilbroner passage, you should give the author's name, the name of the book, the publisher, the date and place of publication, and the page number of the quotation. The whole reference allows the reader to track it down and see what it says for him or herself. It's part of the scientific paradigm that is prevalent in Western societies, which says that convincing evidence about the truth of a hypothesis can be built up only by amassing several independent direct or indirect confirmations of the hypothesis. If I can track down the source, I can see for myself whether I think it is valid. Our reference librarians have put links to citation guides on the web for many types of documents, and for government documents.
Citing books and magazines isn't too hard, but what about stuff like web pages? I try to reference the TITLE of the page, at the top of the document (or perhaps at the topic of your browser window, the URL of the page (its location on the web), the AUTHOR of the page if you can find one (or an organization if it appears that an organization wrote the page), the TITLE and DATE of the broader work if you can discern it, and the date on which you visited the web page. For example, if today is Oct. 1, 1998, you might cite this page as:
Georgetown University Honor Council (1999). What Is Plagiarism? [Online] Georgetown University Honor Council Web Site. URL: http://www.georgetown.edu/honor/plagiarism.html [July. 1, 1999].
There are several problems associated with citing web pages.
* Finding out the proper address to record
If frames are being used, the actual web page address is hidden. In this case you can look at the page properties in Netscape or Internet Explorer to find out the true address. Merely citing the top-level frame address is like citing a whole shelf in the library. It doesn't give the reader enough information to find the page again. Try to think: what will I need to find the address again. I have seen cases where students have copied entire paragraphs from an Internet source and listed the generic top-level web domain (such as http://www.cnbc.com) as the reference. This is far from sufficient for tracking the paper down and could lead to a charge of plagiarism.
* Finding out the author of the page
This may be quite difficult, and you may have to look above or below the page itself in order to find out who it is.
* Finding the page again at all
The web page may disappear tomorrow. If you have not recorded the citation information immediately, waiting until the last minute, you may not be able to find it, ever again. This is a big problem because now you have written the paper, you know at some level you have committed plagiarism, yet you don't want to rewrite the paper. You have painted yourself into a corner. It may be a good idea to download important pages to your computer, keeping them in a folder associated with the paper, or doing printouts of certain pages and keeping them. I use a system for research where I use the URL as part of the file name, so I know exactly where the information came from.
There are several guidelines and style sheets that have been written for citing these new sources, and you should surely consult them. There are some listed on our library's pages. The main idea is that you are giving the necessary information so the reader can track it down himself and read the entire original document. The reader therefore will not have to take your word for it, but can evaluate how you understood and used the evidence that you have presented. Be sure to consult your professor about what is the acceptable citation style.