I run out of cooking idea and look for good cook book for child. Which one should I buy?

If your kid's age above 3 years old, basically he can eat whatever you cook (You just need to reduce the salt/sugar in it) Go check Baby Led Weaning cookbook. It contains more finger food with balanced nutrition. Not only good for your kid's health but also helping his motoric skill http://www.amazon.co.uk/The-Baby-led-Weaning-Cookbook-delicious/dp/0091935288