LKL says: this title, one of the Unesco collection of representative Korean works, is out of print. You can find it it major university libraries.
The 468-page volume contains all of Chinul’s works, translated with an introduction by Robert E Buswell Jr.
The reviewer on Goodreads found it hard going but important.
The volume was abridged as Tracing Back the Radiance: Chinul’s Korean Way of Zen in 1991. Also, it is likely that the most important sections of the volume ended up in the 2016 publication from Hawai’i and Robert E Buswll Jr, Numinous Awareness is Never Dark