@article{CMUC_1989_30_4_a20,
     author = {Ku\v{c}era, Anton{\'\i}n},
     title = {A note on initial segments below $\utilde O'$},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {779--781},
     year = {1989},
     volume = {30},
     number = {4},
     mrnumber = {1045909},
     zbl = {0693.03028},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1989_30_4_a20/}
}