Jan Berenstain, half of the husband-wife team who gave young readers The Berenstain Bears book series, died last week following a stroke. She was 88.

Her son, Mike Berenstain, told The Associated Press that his mother had a stroke on Thursday. She passed away Friday without regaining consciousness, he said.

She outlived her husband and Berenstain Bears co-creator Stan Berenstain, who died in 2005 at the age of 82. She was still working and going strong at the time of her death.

Every day she was very productive, Mike told The AP. She was working on two books and had been doing illustrations until the day before she passed away.

He also said he would continue to work on the books. His older brother, Leo, is also involved in their late parents' work, The AP reported.

The books were centered around a family of bears -- Papa Bear, Momma Bear, Brother Bear, Sister Bear and, later, Honey Bear -- who lived in a treehouse.

The books addressed issues faced by any family and child, including sibling tension, teaching manners and maintaining health.

Not all of the books sat well with fans.

Rob Bricken of ToplessRobot.com noted that some of the series' more bizarre reads included The Birds, The Bees and the Berenstain Bears and The Berenstain Bears and No Guns Allowed.

Still, they were enormously popular and spawned an animated television series, among other franchise products.

Fans of the series expressed grief on Twitter.

Children's scary fiction author R.L. Stine tweeted the following: Did we all read the Berenstain Bears when we were little? Sad to hear that Jan Berenstain, 88, has gone into permanent hibernation.

Here's a clip from a cartoon episode.