@article{,
AUTHOR = {Borowiecki, Piotr and Drgas-Burchardt, Ewa and Sidorowicz, El\.zbieta},
TITLE = {Preface},
JOURNAL = {Discuss. Math. Graph Theory},
FJOURNAL = {Discussiones Mathematicae Graph Theory},
VOLUME = {31},
YEAR = {2011},
NUMBER = {2},
PAGES = {207-207},
ISSN = {1234-3099},
}