#!/usr/bin/python
    print(
    """Acknowledgments: This Python[1] script runs on Linux[2] based operating systems
    and uses the ls (see list-segments[3]) utility, written in the ANSI C[4] language.

    [1] Python programming language, Van Rossum et al., 1991-
    [2] Linux kernel, Torvalds et al., 1991-
    [3] Multics operating system, Corbató et al., 1969-
    [4] C Programming Language 2nd. ed., Kernighan, Ritchie, 1988""")
    ...