Consult the writing manual of choice for your field of study. This should be listed on your syllabus.
Primary Sources are cited based on the format in which you used them rather than by type of content. If you are citing the "Declaration of Independence" found in an anthology of early American documents, then you cite it as a chapter in a book. If you used the copy of the "Declaration of Independence" as shown on the National Archives' website, then you cite it as a document on a website.
For help, use the Library's Citation Help page, talk to your professor, or schedule an appointment with a writing tutor in the LRC, or a librarian.
Anthologies are almost always books, so you create a book citation.
If you are using an anthology that includes one or more primary sources you cited or paraphrased in your paper, or you are using material from an explanatory essay and a primary source, citing the book can be tricky.
The flowchart's left side shows the simplest way of handling primaries used out of an anthology, but it is not always the best way of giving acknowledgement to these sources. Below is an example of what the flowchart's right side shows when referencing the primary source within the text of your paper:
According to Plato in The Republic, "..." as excerpted in Murphy's The Interpretation, this is an example of ....
It is best to cite primary sources directly whenever possible, but it is not always possible to do so, at which point citing a primary source out of a secondary source is acceptable. If you are still unsure as to how to proceed, consult with a librarian or a tutor in the writing center for help tailored to the writing style manual your professor has asked you to use.