How to Write and Publish a Scientific Paper advises writers to use the past tense when they write about unpublished research (including the research their paper reports), and to use the present tense to write about research previously published in a primary journal. So, presumably, writers should use the past tense to refer within their paper.
However, in a reply to this question, a user commented that he uses the present tense when he references within his paper.
- What tense should writers use when they refer within their paper?
- Do arts and humanities papers use tense differently than science papers do?