I have so many art books, between me and my fiancée we have books stacking up, we've run out of shelf space. I have a few suggestions though I don't think I have anything that is specifically geared toward children's illustration. But it's all knowledge that is applied how you desire so. 
If you're looking for books to learn from, I don't think you can do any better than learning from the man, the myth, the absolute legend that is James Gurney. These are fantastic books you could pull from for the rest of your career.
• Color and Light - James Gurney
• Imaginative Realisms - James Gurney
For visual storytelling this book is typically highly recommended.
• Framed Ink: Drawing and Composition for Visual Storytellers - Marcos Mateu-Mestre
I would also recommend checking out used book stores or half price book stores. You would be amazed at how many real gems you could come across. 