Consider using various types of sources, including
• primary sources, or the poets' written works; and
• secondary sources, or books and articles about this era.
Consider using various types of sources, including
• primary sources, or the poets' written works; and
• secondary sources, or books and articles about this era.
Subject-verb agreement means that you use a singular verb with a singular subject and a plural verb with a plural subject, even when a phrase or clause comes between the subject and verb.