Reddit reviews Magic: The Gathering -- Official Encyclopedia, Volume 1: The Complete Card Guide

https://www.amazon.com/gp/aw/d/1560251409/ref=mp_s_a_1_5?ie=UTF8&qid=1501032893&sr=8-5&pi=AC_SX236_SY340_FMwebp_QL65&keywords=Magic%3A+The+Gathering+--+Official+Encyclopedia&dpPl=1&dpID=51R09GTGFDL&ref=plSrch

That's the version I own. They might be slightly different even though they appear to be the same book, so I figured I'd be sure to find my exact copy.

Edit: it appears the version you listed was a reissue from 1999, so it probably does have some differences.

I think I know the book you're talking about, and I did the same thing every summer! All of it seemed so amazing and unique - it's not quite the same looking at gatherer or scryfall today.

According to this blog post, they were printed in this book. I have the book at home and will attempt to verify tonight.

I had this one for a couple years until this bad boy came out

Are you talking about the ones that come in Fat Packs? I ask because these used to be a thing.

The numbers were confirmed in the official mtg encyclopedia. Someone on this forum has a copy and checked it last time we were talking about these numbers :)
https://www.amazon.com/Magic-Gathering-Official-Encyclopedia-Complete/dp/1560251409

Hmm, I haven't thought about it in a long time, but I think that I have this one around somewhere:

Magic the Gathering: Official Encyclopedia

"Every existing Magic card" as of 1996. I wonder if I can still find that around the house somewhere.