Adolescent Dog Snapped At Baby

I wrote to you some months ago and never write again, this because I did not have any problem with my dog until now and this is case of keeping the dog or giving her away.
Last week the dog (9 months now), growled to my 2 year old daughter and to my wife too when she tried to correct her after the action. They were watching TV and it looks like my daughter approached her face to the dog, she has done this before without this kind of reaction and last night she pet her on her back and the dog pull her lips up like if she was ready to bite.
She never growls to anyone and she is very friendly and some times very submissive with people and other dogs.
I'm thinking that this is something to do with my daughter's stature, she is a dwarf and I guess the dog looks at her as lower level because she is actually smaller than the dog.
I read the book trying to find something to do but I see you suggest a professional advice.
I don't want to risk the safety of my daughter or wife, if there is something I can try that you suggest I will appreciate.
Thank you
Guillermo Rodriguez
Dear Guillermo:
I would be careful about letting your daughter be around the dog at this age, however... I would not recommend getting rid of the dog if...
1. You recognize that more than likely, based on what you've told me, you don't have a bad dog. What you've seen is very common amongst young dogs. They are reaching adolescents and are testing out their position in the pack. They are experimenting with new behaviors to see what kind of response it will elicit from the rest of the pack. THIS DOES NOT MEAN THAT YOU SHOULD ENDANGER YOUR CHILD, but rather that you need to keep a very close eye on the two at all times.
She'll likely do this behavior a couple more times. When it happens, it must be met with a no-nonsense, extremely firm correction. (See page 45 and page 174) You must "psych" her into believing that if she tries to harm you or any other member of the pack again, then you will kill her. Make her never, EVER want to even THINK about trying such a behavior again.
2. Let me repeat, this is a very common behavior amongst young dogs. However, your child's safety comes first. I would not let a young child of this age be in direct contact with a dog, period. Regardless of the dog.
Please let me know if there is something you do not understand.
That's all for now, folks!
Adam