There are many places to find articles including library databases, Google Scholar, and on the open web. You will have to look at both the article's citation information and content to decide if it is scholarly or not.
Who is the author? Are they an expert in the field they are writing in? Have they written anything else on this topic or in this field?
What is the journal this article is published in? Does this journal have editorial review? Do scholars pay to get published in this journal? (that may be a sign that this isn't scholarly!)
Who is this written for? Why did they write it: to inform? to persuade? to entertain? to teach how to do something? to give an overview?
Does this article have an abstract? Are there clearly marked sections (Introduction, Methods, Conclusion, etc.)
Does this article include primary source information or research data?
Is there a section on the author's research methods? (researchers usually include methodology to prove they did the actual research!)
Does this article cite other scholarly works? Are there many citations or just a few? Do the citations match the time period and field discussed in the article? Is there a clear citation style?
Not every book published is an academic or scholarly source. Ask yourself these questions to evaluate a book:
Who is the author? Are they an expert in the field they are writing in? Have they written anything else on this topic or in this field?
Who is the publisher? Are they affiliated with a scholarly institution like a university press or reputable research center?
Who is this written for? Why did they write it: to inform? to persuade? tto entertain? to teach how to do something? to give an overview?
Look at the Table of Contents. Does the book contain useful information?
Are there lots of errors or misspellings?
Is this book organized in a logical way? Do the chapters make sense or use language accepted in the field?
Does this book cite other scholarly works? Are there many citations or just a few? Do the citations match the time period in the book?
Questions Adapted from Colorado State Evaluating Books Guide