/usr/share/acl2-6.3/books/textbook/ is in acl2-books-source 6.3-5.
This file is owned by root:root, with mode 0o755.
..
/usr/share/acl2-6.3/books/textbook/chap10/
/usr/share/acl2-6.3/books/textbook/chap10/ac-example.lisp
/usr/share/acl2-6.3/books/textbook/chap10/adder.lisp
/usr/share/acl2-6.3/books/textbook/chap10/compiler.acl2
/usr/share/acl2-6.3/books/textbook/chap10/compiler.lisp
/usr/share/acl2-6.3/books/textbook/chap10/fact.lisp
/usr/share/acl2-6.3/books/textbook/chap10/insertion-sort.lisp
/usr/share/acl2-6.3/books/textbook/chap10/tree.lisp
/usr/share/acl2-6.3/books/textbook/chap11/
/usr/share/acl2-6.3/books/textbook/chap11/compress.lisp
/usr/share/acl2-6.3/books/textbook/chap11/encap.lisp
/usr/share/acl2-6.3/books/textbook/chap11/finite-sets.lisp
/usr/share/acl2-6.3/books/textbook/chap11/how-many-soln1.lisp
/usr/share/acl2-6.3/books/textbook/chap11/how-many-soln2.lisp
/usr/share/acl2-6.3/books/textbook/chap11/mergesort.lisp
/usr/share/acl2-6.3/books/textbook/chap11/perm-append.lisp
/usr/share/acl2-6.3/books/textbook/chap11/perm.lisp
/usr/share/acl2-6.3/books/textbook/chap11/qsort.lisp
/usr/share/acl2-6.3/books/textbook/chap11/starters.lisp
/usr/share/acl2-6.3/books/textbook/chap11/summations-book.lisp
/usr/share/acl2-6.3/books/textbook/chap11/summations.lisp
/usr/share/acl2-6.3/books/textbook/chap11/tautology.lisp
/usr/share/acl2-6.3/books/textbook/chap11/xtr.lisp
/usr/share/acl2-6.3/books/textbook/chap11/xtr2.lisp
/usr/share/acl2-6.3/books/textbook/chap3/
/usr/share/acl2-6.3/books/textbook/chap3/programs.lisp
/usr/share/acl2-6.3/books/textbook/chap4/
/usr/share/acl2-6.3/books/textbook/chap4/solutions-logic-mode.lisp
/usr/share/acl2-6.3/books/textbook/chap4/solutions-program-mode.lisp
/usr/share/acl2-6.3/books/textbook/chap5/
/usr/share/acl2-6.3/books/textbook/chap5/solutions.lisp
/usr/share/acl2-6.3/books/textbook/chap6/
/usr/share/acl2-6.3/books/textbook/chap6/selected-solutions.lisp