Poulsen, E. (2009). Smiling bears: A zookeeper explores the behavior and emotional life of bears. Greystone Books.
芝加哥风格引文Poulsen, Else. Smiling Bears: A Zookeeper Explores the Behavior and Emotional Life of Bears. Vancouver: Greystone Books, 2009.
MLA引文Poulsen, Else. Smiling Bears: A Zookeeper Explores the Behavior and Emotional Life of Bears. Greystone Books, 2009.
警告：这些引文格式不一定是100％准确.