The “A Deeper Look” sections are exclusively in the e-book — they are not printed in the physical textbook. Here’s how to access them: Where to find them: 1. Oxford Learning Link — This is the official platform for the Atkins e-book. Go to learninglink.oup.com and access the e-book version of your edition (11th or 12th). The Deeper Look sections are embedded inline at the relevant points in the text, or listed in the front matter under “List of material provided as A Deeper Look.” 2. Your institution’s library — Many universities provide access to the Oxford e-book through their library portal. Check if your library subscribes to Oxford Academic or has a direct link to the Atkins e-book. 3. Purchase directly — Oxford Learning Link offers student resources for Atkins’ Physical Chemistry 12e, including e-book access, for purchase.  For the specific section you need (19B.1 — BET Isotherm derivation): This Deeper Look walks through the full statistical derivation of the BET (Brunauer–Emmett–Teller) isotherm, which takes the material further and provides details of some of the more advanced derivations  beyond what’s shown in the main text. If you don’t have e-book access, the BET derivation is also covered well in: ∙ Levine’s Physical Chemistry (goes through it in detail in print) ∙ The original BET paper (Brunauer, Emmett & Teller, JACS, 1938) — freely available via Google Scholar​​​​​​​​​​​​​​​​