What would be an example of a persuasive speech supported by credible sources?

I would say that one of the most persuasive speeches in American
History that possessed creditable sources and analysis was Dr. King's "I Have a Dream" speech. I
thought that one of the most credible sources that King featured was the use of American History
as part of his argument. In trying to convince his audience and all Americans that Civil Rights
was an issue embedded in the American History, King was able to persuade his audience that the
issue of "Civil Rights" was actually an issue of human rights. The historical concepts that
involved invoking the Founding Fathers, the linking of civil rights as being representative of
the "bedrock of U.S. political and social character," and the notion of the delivering of civil
rights as a "promissory note" were all examples of Dr. King using the most credible of sources to
convey his point. The idea of using American History as part of his argument helped to enhance
the persuasive element in his speech, and helped to make it a part of the American History from
which it reverberates.