It depends on how formal you all are within your work group. Less formally you can write the following. Reminder: You were going to send us the documents on stream-of-consciousness and the MLA handbook for research writers (7th edition).
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kunsusukiThe level of formality is too high.The level of formality of which? Your email or mine?
kunsusukiWould the previous e-mail be appropriate?Both your email and my email are "previous" to your post. Which one are you referring to?
kunsusukiThis message comes as a reminder of the documents of stream of consciousness and the seventh edition of MLA handbook for research writers.No, this won't do because it doesn't mention sending. The whole point is to remind your supervisor to send these things. Maybe like this, which is almost exactly the same as yours: