Question: Julia Donaldson's illustrated children's books include Room on the Broom, Stick Man and which story that has sold 13 million copies?
Context: Stick Man written by erstwhile Children's Laureate, Julia Donaldson, and illustrated by Axel Scheffler is a children's story about a anthropomorphic wooden stick who becomes separated from his family home and his "Odyssey"-like adventure to return there.  He is eventually reunited with his family in the "family tree" as a result of his interaction with Father Christmas. This list of "Berenstain Bears" books includes many in the picture book series (such as "Beginner Books" and "First Time Books") and the illustrated children's novels, such as those in the "Big Chapter Books" series.  Since the first "Berenstain Bears" installment was published in 1962, the series has sold close to 260 million copies. Monkey Puzzle by Julia Donaldson and Axel Scheffler is an illustrated children's book. Room on the Broom is a British children's book by writer and playwright Julia Donaldson, illustrated by Axel Scheffler, which tells the story of a kind witch and her cat who invite a number of other animals to join them whilst traveling on her broomstick. Julia Donaldson MBE (born 16 September 1948) is a Scottish writer, playwright and performer, and the 2011–2013 Children's Laureate.  She is best known for her popular rhyming stories for children, especially those illustrated by Axel Scheffler, which include "The Gruffalo", "Room on the Broom" and "Stick Man".  She originally wrote songs for children's television but has concentrated on writing books since the words of one of her songs, "A Squash and a Squeeze", were made into a children's book in 1993.  Of her 184 published works, 64 are widely available in bookshops.  The remaining 120 are intended for school use and include her Songbirds phonic reading scheme, which is part of the Oxford Reading Tree. The Snail and the Whale is a children's book by former children's laureate Julia Donaldson, illustrated by longtime collaborator Axel Scheffler.  It has won several awards, including 2004 Early Years award for the best pre-school book, the 2005 Blue Peter award for Best Book to Read Aloud, and the 2007 Giverny award for Best Science Picture Book.  "The Snail and the Whale" has also been adapted into an audiobook, a successful stage play and translated into British Sign Language. The Gruffalo is a children's book by writer and playwright Julia Donaldson, illustrated by Axel Scheffler, that tells the story of a mouse, the protagonist of the book, taking a walk in a European forest.  The book has sold over 13 million copies, has won several prizes for children's literature, and has been developed into plays on both the West End and Broadway. Eric Carle (born June 25, 1929) is an American designer, illustrator, and writer of children's books.  He is most famous for "The Very Hungry Caterpillar", a picture book that has been translated into more than 62 languages and sold more than 44 million copies, which is equivalent to one copy sold every minute since it was published.  Since it was published in 1969 he has illustrated more than 70 books, most of which he also wrote, and more than 138 million copies of his books have been sold around the world.  He won the biennial Laura Ingalls Wilder Award for his career contribution to American children's literature in 2003. Animalia is an illustrated children's book by Graeme Base.  It was originally published in 1986, followed by a tenth anniversary edition in 1996, and a 25th anniversary edition in 2012.  Over three million copies have been sold.  A special numbered and signed anniversary edition was also published in 1996, with an embossed gold jacket. Room on the Broom is a 2012 British-German 3D stop motion computer animated short TV film based on the picture book written by Julia Donaldson and illustrated by Axel Scheffler.  The film was nominated for the Best Animated Short Film at the 2014 Academy Awards.
Answer: The Gruffalo