Final answer:
Primary sources, long-form journalism, professional/trade articles, and secondary sources are common types of sources used in academic papers. So, all the options are correct.
Step-by-step explanation:
Academic papers draw upon a variety of sources to substantiate claims and enhance scholarly discourse.
Primary sources, encompassing materials like diaries, letters, interviews, and original research data, serve as the foundational bedrock of firsthand information.
Another valuable resource is long-form journalism, comprising extensive articles that delve deeply into topics, presenting comprehensive and thoroughly researched insights.
Expertise is often encapsulated in professional or trade articles, where specialists within a particular field contribute to industry-specific journals or magazines, lending authoritative perspectives.
In contrast, secondary sources play a pivotal role by synthesizing and interpreting information gleaned from primary sources.
Textbooks, scholarly articles, and encyclopedias fall under this category, offering analyses and contextualization that enrich the academic discourse.
Hence, all the options are correct, Primary sources, long-form journalism, professional/trade articles, and secondary sources are common types of sources used in academic papers.