The first is that the cover is a forest green with a sort of light lime green text. Not Black-ish.
The paper over time has aged to be yellow which is very common from books of that time period. Also there are sort of blackish spot splatter texture on the paper edges for decorative purposes.
Next The model itself is too thin. The books actual Dimension are about 9x6x2.5 inches ( 22.86 x 16.24 x 6.35 Centimeters ) the book appears in game as being about the 1.5 times widths and height but only about half the size depth.
the fact that the book s show with it's dust cover on and that there is only the spine title on it with out the dust cover, it's kinda no big deal to just sans the dust cover in the model. but the spine and front of the book should be a forest green rather then black and the book thickened to represent the actual thing that is shown on the SCPwiki and in real-life.
Heck you can buy this book still for a few US Dollars, and i plan on doing just this very thing for love of the SCP lore. My folks wont part with their copy sadly.
Spoiler
Here is the more accurate depiction of the book. I have taken some liberties with the Publishers Name and Logo, as well as the back cover as i can't remember exactly what it says and the one image i have found online lacks detail to read it and has a big light flare making most of it unreadable. My version lacks the Spots Splotches as of yet but the model i nearly done and a new Normal map is almost ready.There are jokes on the back cover in this version.
Spoiler
Maybe I'll release this new version for Undertow to use in future updates. but first i need to make a High Poly version and bake the normals of that into the Nomal Map of the Low Poly version.The model shown only has 68 tris.