/usr/share/kde4/apps/klettres/sk.txt is in klettres-data 4:4.13.0-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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Á Ä Č Ď É Í Ĺ Ľ Ň Ó Ô Ŕ Š Ť Ú Ž