I was wondering if a list of classifying adjectives of the same type could use the Oxford Comma.
For example: social, political, and economic problems is it a correct expression? I was checking a book and the expression they used is social, political and economic problems.
Another example: The tulips were yellow, orange and red. Can I use The tulips were yellow, orange, and red?
Does the Oxford Comma rule apply in those cases? Are they both valid?