/usr/share/acl2-7.2dfsg/books/projects/hybrid-systems/ is in acl2-books-source 7.2dfsg-3.
This file is owned by root:root, with mode 0o755.
..
/usr/share/acl2-7.2dfsg/books/projects/hybrid-systems/abs.lisp
/usr/share/acl2-7.2dfsg/books/projects/hybrid-systems/arith-nsa4.lisp
/usr/share/acl2-7.2dfsg/books/projects/hybrid-systems/cert.acl2
/usr/share/acl2-7.2dfsg/books/projects/hybrid-systems/computed-hints.lisp
/usr/share/acl2-7.2dfsg/books/projects/hybrid-systems/eexp.lisp
/usr/share/acl2-7.2dfsg/books/projects/hybrid-systems/example.lisp
/usr/share/acl2-7.2dfsg/books/projects/hybrid-systems/nsa.lisp
/usr/share/acl2-7.2dfsg/books/projects/hybrid-systems/o-real-p.lisp
/usr/share/acl2-7.2dfsg/books/projects/hybrid-systems/phi-exists.lisp
/usr/share/acl2-7.2dfsg/books/projects/hybrid-systems/phi-properties.lisp
/usr/share/acl2-7.2dfsg/books/projects/hybrid-systems/phi-unique.lisp
/usr/share/acl2-7.2dfsg/books/projects/hybrid-systems/tm-floor.lisp