You don’t have to have three concepts. You can have more or fewer, but try to begin with at least two.
Think of Other words
What are some words that mean almost, but not quite, the same thing as your main ideas? If you do not find many results for one search, do not give up quite yet. You can change the words a little bit to find more articles or more specific articles. Think of synonyms, alternative spellings, and related ideas.