I wanted to buy it - I don't remember exactly, but I think I couldn't find an e-book version, and the paper one was expensive and didn't even ship to my country :( I hope to be wrong on that, though, do you know if there's an ebook available from somewhere?
Other than the online version (4th edition), I don't know of any other place to get it. Yes, the paperback was expensive, but I bought it anyway. It proved to be very informative and more substantive than I had thought. I believe the 5th edition is almost ready for publication.
I'm an idiot. I looked at this page: https://shenlanguage.org/TBoS/tbos.html many times, tried clicking on the table of contents, realized that chapter titles are not links, and went away thinking it's only the ToS for promotional purposes. I only realized that the page numbers are links just now. To my defense, they don't differ in color that much and lack the underline that often marks links. Still, a HUGE facepalm :D Thanks for mentioning this and making me realize my own stupidity :)
Glad you found it. I've done much worse, believe me!
If you have any questions check out the Google Groups (no Groups comments!) for Shen. I am eager to see the 5th edition, and I will probably buy the print version.
