You may also consider asking a similar question on the various 'Ask a question' websites, but obviously the responses to a shotgun approach will vary wildly.

Thank you for this idea. I submitted a variant of my post to Health Stack Exchange.

...you may want to provide an easy way for someone to contact you without creating a LW account in case of the useful but lazy passerby.

I've edited my post to include contact information.

If you have boldness, why not contact the writers of the textbook and ask them?

I will contact them tomorrow, but I don't expect much from cold-emailing researchers.