Secondary sources 2.3 Secondary sources usually form the main or sole basis for the majority of undergraduate essays. Secondary sources are best defined as books, articles and other commentaries written later in time about a particular subject, most often by professional and amateur historians or journalists, which interpret the nature and significance of the primary sources. Secondary sources on the origins of the First World War would include the vast number of books studying the events leading up to August 1914; biographies of the major political and military figures of the time; studies of popular opinion and attitudes towards war in the main European states; more focused articles on specific questions published in journals such the English Historical Review or War in History; modern maps detailing the movement of armies during the build-up to war; book reviews which provide overviews and critiques of the main developments in the study of the subject; and so on.
2.4 There are good and bad secondary sources for essays. Good secondary works are firmly based upon a large range of relevant primary sources and have been subjected to careful review before being published by reputable presses; bad ones tend not to have been subjected to processes of scrutiny or are supported by only a weak base of primary research. Thus, you should critically evaluate the usefulness of each source as you proceed with your research. Who was the author and who was the publisher? When was it published and who was the intended audience? Does it have extensive footnotes and a relevant bibliography? What sorts of sources has the author used to support their argument? What sorts of unspoken assumptions, or detectable biases, might be at work? Is the argument still relevant? For example, you would read an American book published in 1999 about relations between the United States and the Soviet Union during the Second World War quite differently from a book on the same subject published in Moscow in 1957.
2.5 Textbooks and encyclopaedias should not serve as the main sources for your essay research. They are generally too basic, not well-referenced and provide only facts without analysis. (On-line encyclopaedias are no more acceptable as sources for research essays than are standard printed encyclopaedias—especially the worst example of all, Wikipedia!) So, too, with works of ‘popular history’: though often fun to read, they are not usually a good source for further research. Finally, neither should your lecture notes serve as the foundation for your research—certainly never quote from them in your essays!—for any important point made in a lecture should be tracked down and explored in proper detail by you in published sources.