So, you've broken down the question. You've thought of different words and phrases to search. You know which databases to search. And tried some Boolean techniques. Remember to persevere with your searching. Try different combinations. It may take a few attempts and some time to find what you're looking for. A good literature search takes time and patience.
Can you tell the difference between a good website and a bad website?
How can you evaluate whether the website you are looking it is a credible source to use in academic work or assignments?
The links below might help.
Q: "I'm getting thousands of results. How can I narrow my search down?"
A: Try limiting your results e.g.
... to peer reviewed articles/ books available in the library...
...to different years...
...to language...
Remember that many of the databases that you'll be searching will have help screens and 
options.