I am writing an academic paper and, at a certain point, I want to write: "Firstly,... Then, ... Next, ... Lastly...."
However, "Then" and "Next" at the beginning of phrases sound like very INFORMAL English. I need FORMAL alternatives. What do you suggest/use?
I know this article suggesting "First... Second... Third... Lastly...": First, Second, Third, and Finally But I already used this structure somewhere else in the text, so I want to avoid repetition.
Thank you.