Gaya APA
Helldorfer, M, C. (1983).
The work trap: Solving the riddle of work and leisure. .
Whitinsville:
Whitinsville Affirmation Books.
Gaya MLA
Helldorfer, Martin, C..
"The work trap: Solving the riddle of work and leisure. ".
Whitinsville:
Whitinsville Affirmation Books,
1983.
Buku.