@article{Hakimi1961, 
     author = "Hakimi, S.L.", 
     doi = "10.1016/0016-0032(61)90036-9", 
     issn = "00160032", 
     journal = "Journal of the Franklin Institute", 
     link = "http://linkinghub.elsevier.com/retrieve/pii/0016003261900369", 
     month = "nov", 
     number = "5", 
     pages = "347--359", 
     title = "On trees of a graph and their generation", 
     uri = "http://linkinghub.elsevier.com/retrieve/pii/0016003261900369", 
     volume = "272", 
     year = "1961", 
}

Problems: 391