Sinkhole is available from all major wholesalers and Hopkins Fulfillment Services
In Canada, contact UTP.
Sales Representation:
https://www.hfsbooks.com/about/hopkins-sales-partners/
You can order direct from HFS by Phone (8:30-5:00 EST) 800-537-5487 or by email hfscustserv@jh.edu.

Paperback
$18.95 USD (trade discount)