Here are the publications I found most valuable in researching Kwan Yin (or Kuan Yin or Quan Yin or Guan Yin), the Chinese goddess of mercy and compassion. Most links are for more info at Amazon.com, an affiliate.
Discovering Kwan Yin: Buddhist Goddess of Compassion, by Sandy Boucher, Beacon, Boston, 1999. A brief and charming introduction to the goddess, with a look at some contemporary Western worshipers.
Kuan Yin: Myths and Prophecies of the Chinese Goddess of Compassion, by Martin Palmer and Jay Ramsay with Man-Ho Kwok, HarperCollins, London, 1995. Though over half of this book is wasted on a system of divination associated with Kwan Yin, the book begins with an excellent introduction to the goddess. It’s especially valuable for the collection of legends and folktales that feature her.
Bodhisattva of Compassion: The Mystical Tradition of Kuan Yin, by John Blofeld, Shambhala, Boston, 1977. The spiritual odyssey of a learned traveler in Asia. This is the classic that helped bring Kwan Yin to the West. Also included is Tara, Kwan Yin’s playful Tibetan cousin.
Kuan-yin: The Chinese Transformation of Avalokitesvara, by Chün-Fang Yü, Columbia University, New York, 2001. The most comprehensive scholarly study of Kwan Yin ever published. This may be more than you want to know!
The Legend of Miaoshan, by Glen Dudbridge, Oxford University, 2004 (revised edition of The Legend of Miao-shan, 1978). A study of the popular but specious origin legend of the goddess.
“Puto, the Enchanted Island,” by Robert F. Fitch, in National Geographic, March 1946. A fascinating account of a visit to one of Kwan Yin’s fabled homes, a popular place of pilgrimage.