my family which made it possible for me to study in Graz.

Eranda Çela for her permanent support and for her help in my master’s and doctoral studies. She also made it possible to focus on my favourite research subject during my doctoral studies.

Ulrich Pferschy for his support in my doctoral studies and for his valuable research impulses, which led to a number of joint publications.

Peter Greistorfer for his support in doing my research and also for the possibility to choose the topics I focused on in my work.