Boolean Operators are short words used to combine search terms in logical operations. Most databases, discovery layers and search engines recognize them and use them to to bring search results that fulfill the requested operations.The most common are AND, OR and NOT. They are written in capitals to differentiate them from regular keywords.
Check the image below to understand how each of them affects the results of your searches. Parenthesis are used to combine different sets of instructions and to signal the order in which they should happen.
Here are a few criteria for determining if your source is scholarly:
Author(s) credentials - are they experts working or teaching in this field of study?
Length - is it a few brief paragraphs or a longer, more substantive article?
Language - is it written for other scholars in the field? Do they used specialized or technical language specific to this field of study?
References - is the author(s) citing other scholars in this field of study? Do they have a robust reference list?
Journal or Book Type - If it's a journal article, what kind of journal is the article is published in? Is it a scholarly journal, or even peer reviewed? If it’s a book, is it published by a university press or other well-respected commercial publisher known for publishing scholarly works?
Research Article: Primary literature article where the main focus is research, experiments or theory similar to a lab report. The article is narrow in scope and often cited within reviews. It is less connected with the literature discussion. The authors describe experiments that they did. A methodology/ experimental section is included.
Review Article: Secondary literature where the main focus is the literature and what is being discussed on a topic. They are often cited within background or introductions of research articles to help others come up to date. They are a good entry point into the literature on a topic and are broad in scope similar to an encyclopedia article. The authors summarize and evaluate other research. Methodology could include what searches were used and what documents were included or excluded and why.