I found a set of (still!) shrink-wrapped flashcards for Series 90 brief forms and derivatives on Etsy! The sheets are perforated so that they can be separated into individual cards. I scanned them in before separating them, in case others might like to use this as a study aid, too.
You will need to print these two-sided, except for the cover. Each card has a printed word on it for the brief form on the reverse side. You will need 7 sheets of cardstock (don’t print the cover sheet). As the cover states, this set includes 115 brief forms and 11 derivatives.
Happy studying!
Attachment: Brief Forms Flash Cards (1978).pdf