Genealogy / Looking for a person living in Warsaw - any online phone book in Poland? [33]

I would like to try and find my cousins who used to live in Warsaw (they may still do so), their names were Ewa & Krystyna? Ptaszek. Krystyna was married with a daughter called Marta. Ewa was not married when I last saw her and her ambitions were to open her own hairdressing salon. Their parents were Lonek and Honerata Ptaszek and they came from Pultusk. She stayed with us for a year to learn English and was going to work in a hotel to begin with. Any help would be gratefully received. Her last known address was Ul Olbrachta 15/19, Warszawa 01-111, Poland