My colouring books 'Mermaids' and 'Merfolk' are both available as physical items for purchase through Amazon (and hopefully major book retailers if you ask for the titles specifically, if I set things up properly).
Digital versions of individual pages are available via my etsy store, TimCookArt.
I would be thrilled if you or anybody did use the same (or similar) style of mermaid as mine! The reason I made the skeleton and musculature studies was in the hope that others would be inspired to make more anatomically-sensible mermaids. Enough mermaid drawings have knee-joints and separated buttocks for no good reason!