Jackie Gaff. (2005). I Wonder Why Pine Trees Have Needles: And Other Questions About Forests. Gardners Books.
Cita Chicago (17th ed.)Jackie Gaff. I Wonder Why Pine Trees Have Needles: And Other Questions About Forests. Gardners Books, 2005.
Cita MLA (9th ed.)Jackie Gaff. I Wonder Why Pine Trees Have Needles: And Other Questions About Forests. Gardners Books, 2005.
Atenció: Aquestes cites poden no estar 100% correctes.