Award-winning US author Joanna Cole, who wrote “The Magic School Bus” series and other children’s books, has died at the age of 75.

Cole lived in Sioux City, Iowa, and died on July 12, according to a statement from her publisher, Scholastic, sent on Thursday.

She was best known for “The Magic School Bus,” a science series that she launched in 1986 with illustrator Bruce Degen.

“What Joanna has meant to the world, what there is in the world because of her, is well known,” said Degen. “What she meant to me I can’t describe. Everyone who knew her, worked with her, loved her, knows what a loss it is.”

The series has 13 core titles and dozens more connected titles, and there are more than 93 million copies in print across 13 countries, according to Scholastic.