A frequent worry in the mind of viva candidates is that their examiners will say something like:
I was really surprised that you didn’t mention Famous Paper X by Professor Important in your literature review…
What if your examiners say that you’re not cited something important? What then?
Well, that’s their opinion. Your examiners are in the viva to have opinions and ask questions. You’ve not thoughtlessly compiled and read the papers that you have to help support your research. You have reasons for citing the articles that you have, and you have reasons for not citing the articles that you haven’t.
If you’ve intentionally not included Famous Paper X then discuss why – and then explore the papers that you have referenced.
Remember, there will be a lot of papers relevant to your field, it isn’t possible to read them all. If you’ve not read Famous Paper X or not heard of it then ask questions. Why does your examiner think it is important? What do they think it would have added? Listen, and then discuss with them all of the papers or work in your thesis that is relevant to their point.
The viva is an exam disguised sometimes like a conversation. Some questions are testing, others are exploratory. Your examiners might have a different opinion, but they can’t claim that you’ve not done the work. Listen to questions, listen to comments, listen to opinions. Then respond.