Amy Shields. (2011). National Geographic Readers: Trains. National Geographic Children's Books.
芝加哥风格引文Amy Shields. National Geographic Readers: Trains. National Geographic Children's Books, 2011.
MLA引文Amy Shields. National Geographic Readers: Trains. National Geographic Children's Books, 2011.
警告：这些引文格式不一定是100％准确.