@ARTICLE{
author={Plancak Miroslav E,Vollertsen F,Woitschig J},
year={2005},
title={Analysis, finite element simulation and experimental investigation of friction in tube hydroforming},
journal={JOURNAL OF MATERIALS PROCESSING TECHNOLOGY},
volume={170},
number={1-2},
pages={220-228},
document_type={Article},
} 

@ARTICLE{
author={Vollertsen F,Plancak Miroslav E},
year={2002},
title={On possibilities for the determination of the coefficient of friction in hydroforming of tubes},
journal={JOURNAL OF MATERIALS PROCESSING TECHNOLOGY},
volume={125},
number={},
pages={412-420},
document_type={Proceedings Paper},
}