Textbooks readings on thermochemistry from both textbooks are difficult to read. Remember the survival skill tutorials? Misunderstood words and symbols can really take a toll on you. This section has plenty of symbols and words that are not easy to understand. My tutorials covered a good portion of what is in these sections but not all of it. All I can say is read them at your own risk. Be aware of the negative feelings you may experience: dislike of the subject, feeling of being stupid, feeling like dropping chemistry, headache, eye pain, heavy weighed down feeling, and more). These symptoms just come with the territory when you encounter something new and challenging. You have to use all of those countermeasures I mentioned in those survival tutorials.
If the readings don't make a lot of sense, realize that this topic is usually not learned just by reading one textbook. You may just want to do the quiz because it doesn't go into all of the detail that's covered in the textbooks.
For all editions of Zumdahl
The first 4 sections of chapter 6 (Thermochemistry) in Zumdahl's books are difficult to read. I hesitate to assign any readings of those sections because they may be more confusing than enlightening.
For all Editions of Tro:
Nivaldo Tro does a much better job than Zumdahl's book at explaining thermochemistry, but you will still encounter a lot of new symbols and words.
Read chapter 6 but, again, expect a lot of headaches.
For all editions of Zumdahl's books, read the following sections
Section 6.5: Present Sources of Energy
Section 6.6: New Energy Sources