Soon after the founding of Amazon.com in 1995, I began offering the following research tip to my journalism students.

When reporting about a person or a topic, especially when the subject is controversial, go to Amazon.com and type in two or perhaps three search terms — including a proper name or the keyword linked to the topic you are researching.

Of course, reporters should do broader searches online and in professional-level periodical collections — looking for experts and activists on both sides of the story being covered. What an Amazon.com search gives you is a look at who has been doing, well, book-length studies of a person or a topic.

So let’s take a look at an Amazon.com search linked to this week’s “Crossroads” podcast (click here to tune that in). Let’s search for “Margaret Sanger” and “eugenics.” We are looking for sources that could have been used in the New York Times piece that ran the other day with this sobering double-decker headline:

Planned Parenthood in N.Y. Disavows Margaret Sanger Over Eugenics

Ms. Sanger, a feminist icon and reproductive-rights pioneer, supported a discredited belief in improving the human race through selective breeding

That’s a very controversial topic and this Times piece, we shall see, includes some rather blunt information about this “icon” of the cultural left.

What the story does not contain, however, is a single quote from a scholar or activist who has done years of research to gather information critical of Sanger and her legacy in American life and culture.

Right at the top of that Amazon.com search are books by two experts who, to my eyes, look solid.

One book is entitled “War Against the Weak: Eugenics and America's Campaign to Create a Master Race.” The author is not a scribe at a right-wing think tank. Instead, Edwin Black — on his Amazon.com biography page — is described as:

Edwin Black is the award-winning, New York Times and international investigative author of 200 bestselling editions in 20 languages in more than 190 countries, as well as scores of newspaper and magazine articles in the leading publications of the United States, Europe and Israel.