APA Style
Spyri, Johanna. ().
Heidi .
London:
Penguin Books.
Chicago Style
Spyri, Johanna.
Heidi.
London:
Penguin Books,
.
Text.
MLA Style
Spyri, Johanna.
Heidi.
London:
Penguin Books,
.
Text.
Turabian Style
Spyri, Johanna.
Heidi.
London:
Penguin Books,
.
Print.