«Mac OS X Leopard - Technology - UNIX». Leopard Technology Overview. Apple Inc. Arkivert fra originalen 27. desember 2008. «Leopard is now an Open Brand UNIX 03 Registered Product, conforming to the SUSv3 and POSIX 1003.1 specifications for the C API, Shell Utilities, and Threads.»
github.com
«Release 1228». 30. oktober 2007. Besøkt 9. januar 2023.
«Mac OS X Leopard - Technology - UNIX». Leopard Technology Overview. Apple Inc. Arkivert fra originalen 27. desember 2008. «Leopard is now an Open Brand UNIX 03 Registered Product, conforming to the SUSv3 and POSIX 1003.1 specifications for the C API, Shell Utilities, and Threads.»