single book, search results

https://github.com/zotero/translators/blob/2b80453e21f7e43417427fa5b744a80404c4c237/Factiva.js#L38 https://github.com/zotero/translators/blob/7faaf2dc0b78d6a4a1caece78b5d9721d0ca0b16/Wiley%20Online%20Library.js#L392 for some examples

https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver#MutationObserverInit for second parameter options (defaults to `{childList: true, subtree: true}`, which is a bit overzealous in most cases)