What do you call the invisible part of an iceberg?

MLA

Le Restif, Claire, et al. What Do You Call the Invisible Part of an Iceberg?. 1000 ex. Barcelone: Policrom, 2003.

APA

Le Restif, C., Gauthier, M., Bellido, R. Tio, & Perret, C. (2003). What do you call the invisible part of an iceberg?. 1000 ex. Barcelone: Policrom.

Chicago

Le Restif, Claire, Michel Gauthier, Ramon Tio Bellido, and Catherine Perret. What Do You Call the Invisible Part of an Iceberg?. 1000 ex. Barcelone: Policrom, 2003.