While most children's books end on a happy note ("Goodnight, Moon!"), the reality of how they come to be is much more depressing.

According to a new report issued by the Rainforest Action Network, the majority of four-color children's books are still being produced using paper fiber linked to the destruction of endangered rain forests.

The organization tested a random sampling of 30 books from the top 10 U.S. children's publishers, and found that 18 of them contained fibers linked either to tropical hardwoods or acacia pulp wood plantations in Indonesia. Much of this is related to the industry relying heavily on Chinese-based manufacturers for low-cost production.

"The use of rain forest paper can be traced to the buying practices of these Chinese manufacturers," writes Rebecca Tarbotton, executive director of RAW. "China is the top importer of Indonesian pulp and paper, and much of the Chinese paper industry is linked to or controlled by highly controversial Indonesian pulp and paper suppliers."

She adds: "Indonesia's rain forests are some of the most valuable on Earth, both because of their high ecological value and because of their importance to stopping climate change."

Rainforest Action Network released the report in advance of Book Expo America, the annual trade show for the book industry, which opened Tuesday at the Javits Convention Center in New York City. The organization is offering a petition for people to sign to ask U.S. publishers to use rain forest-free paper.