@Unpublished{	  Bunde_optimal,
  author	= {Bunde, David P. and Chambers, Erin W. and Cranston, Daniel
                   and Milans, Kevin and West, Douglas B.},
  title		= {Pebbling and Optimal Pebbling in Graphs},
  note		= {(Preprint)}
}

@article {Moews,     
AUTHOR = {Moews, David },      
TITLE = {Pebbling graphs},    
JOURNAL = {J. Combin. Theory Ser. B},   
FJOURNAL = {Journal of Combinatorial Theory. Series B},     
VOLUME = {55},       
YEAR = {1992},     
NUMBER = {2},     
PAGES = {244--252},       
ISSN = {0095-8956},      
CODEN = {JCBTB8},    
MRCLASS = {05C35},   
}