dear Justyna,
the following book.. I recommend ( price vv quality = great)

Physical Therapy for Children 3rd edition
authors are:Suzann Campbeel, Darl vander Linden and Robert Palisano.
It is made up of more than 1100 pages and includes a DVD which is really informative.
If you absorb all the information inside... you will know lots more...
isbn 13:978 0 7216 0378 0
and 10: 0 7216 0378 0
can be ordered and sent to you through www.elsevier.com

happy reading
esther