In place of a traditional Ref Sheet is this collage of 5 of my current favorite images of the Red Fox Squirrel.
For a general Fur Pattern/Marking guide see my 'Temp Ref'.
For NSFW needs there are plenty of images in the gallery.

Artists for these images include
 black-kitten
 sailoranna (with coloring by me) (Lilly is also © to SailorAnna)
 foxboy83 (with coloring by me)
 Taillone (with coloring by me)
 Ajna modified by  Ami~ (and with color edits by me)