Primary sources are original texts or resources recording an event as it occurs. For example, in the discipline of literature, primary sources could include autobiographies, novels, works of poetry, and diaries, journals and letters by the author.
Secondary sources provide analysis, commentary, and critique of the author and the work. Many nonfiction books are secondary sources. Biographies and review articles and essays are secondary sources. Some resources will be a combination of biography and criticism.
You can search the library system with the author you are writing about as the subject. The bibliographies listed in biographies point to other sources that may prove to be helpful in your research.
American Writers by 
British Writers by 
Contemporary Authors by 
Cyclopedia of Literary Characters by 
Characters in 19th-Century Literature by 
Characters in 20th-Century Literature by Literature Criticism from 1400 to 1800 by 
Nineteenth-Century Literature Criticism by 
Twentieth Century Literary Criticism by Contemporary Literary Criticism by Critical Survey of Long Fiction, English Language Series by Critical Survey of Short Fiction by Masterplots II. American Fiction series by Masterplots II. British & Commonwealth series by Masterplots II. Drama series by Masterplots II. European Fiction series by Masterplots II. Poetry series by Masterplots II. Short Story series by Masterplots II. World Fiction series by Masterplots II. 2010 Plot Stories & Essay Reviews from the World's Finest Literature by The Harvard Concordance to Shakespeare by A concordance to the poetical and dramatic works of Alfred, Lord Tennyson, including the poems contained in the "Life of Alfred, Lord Tennyson," and the "Suppressed poems, " 1830-1868 by 
The video tutorials below will help you in understanding the search features and process for each of the listed article databases. If you have additional questions or need further assistance please contact a librarian (library@nnu.edu).
Tertiary sources are those which include both primary and secondary types of information. Examples of these sources would be, Archive collections, bibliographies, dictionaries, and encyclopedias.
Archive collections are a great source of information. These collections contain mostly primary sources, but may also include secondary sources. Archive collections are usually affiliated with universities, public libraries, and museums. Some of the content in these collections may be digitized. For content that is not digitized you may need to contact the archivist (the person in charge of the archive collection) find out the best method for accessing the content/information you need. Below are some sample searches for a variety of archive collections. The video below discusses and demonstrates the use of bibliographies and archive collections in the course of literary research.
Bibliographies are great sources to glean other works that you may not have discovered through other search mechanisms. Bibliographies are collections of works on a particular topic. Sources used by authors to create works are located in bibliographies at the end of the work. Topical bibliographies, such as Civil War Literature, 1861-1914, has a specific research focus, but may be helpful if you are writing about Harriet Beecher Stowe, as it may include primary and secondary sources on her and her writings. The short video below will demonstrate how to search the library system to locate resources both in NNU library and in other libraries (that you can request through interlibrary loan).
Stephen Crane: A Critical Bibliography by 
Contemporary Novelists by The following link is a search done in the NNU Riley Library system for encyclopedias-related to American Literature.
The following link is a search done in the NNU Riley Library's system for dictionaries related to American Literature.
To locate companions, dictionaries, encyclopedias, and handbooks for other literatures (e.g., British literature), use the following search strategy format in the library system:
su:British literature--encyclopedias (dictionaries)
Remember to limit your search results to items owned by NNU Riley Library.
Encyclopedia of World Literature in the Twentieth Century by 