Bibtex of Graph / Kernel

@article{Frangakis1981, 
     author = "Frangakis, C.N.", 
     doi = "10.1080/00207168108803264", 
     issn = "0020-7160", 
     journal = "International Journal of Computer Mathematics", 
     month = "jan", 
     number = "1", 
     pages = "35--41", 
     title = "A backtracking algorithm to generate all kernels of a directed graph", 
     volume = "10", 
     year = "1981", 
}

@article{Szwarcfiter1994, 
     author = "Szwarcfiter, Jayme L. and Chaty, Guy", 
     doi = "10.1016/0020-0190(94)00072-7", 
     issn = "00200190", 
     journal = "Information Processing Letters", 
     month = "aug", 
     number = "3", 
     pages = "149--153", 
     title = "Enumerating the kernels of a directed graph with no odd circuits", 
     volume = "51", 
     year = "1994", 
}