@article{Hakimi1964, 
     author = "Hakimi, S. and Green, D.", 
     doi = "10.1109/TCT.1964.1082276", 
     issn = "0018-9324", 
     journal = "IEEE Transactions on Circuit Theory", 
     link = "http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=1082276", 
     number = "2", 
     pages = "247--255", 
     title = "Generation and Realization of Trees and k-Trees", 
     uri = "http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=1082276", 
     volume = "11", 
     year = "1964", 
}

Problems: 431