there are a lot of books about SF - her just three of them i like:))
Coaching Plans & Simple (Peter Szabo/Daniel Meier) (Norton & Company / ISBN 987- 0-393-70593-5)
Brief Coaching - A Solution Focused Approach (Chris Iveson et al / 2012 / Routledge / ISBN: 978-615-80268-3-3)
More Than Miracles: The State of the Art of Solution-Focused Brief Therapy (Steve de Shazer / Yvonne Dolan / Routledge Mental Health Classic Editions / ISBN-13: 978-0789033987)
I know you are working with children and the videos and resources from Ben Furman might be interesting for you. He has developed Kid's skills. It was translated in many languages and I think you even find it in Romanian. https://benfurman.com/WP2/videos/
Also there are some good videos from Chris Iveson and Evan George on the internet. They have written the book that Daniel mentioned, and work both at the BRIEF institute in London.