@article{Andrzejak,
title = "Splitting Formulas for Tutte Polynomials ",
journal = "Journal of Combinatorial Theory, Series B ",
volume = "70",
number = "2",
pages = "346 - 366",
year = "1997",
note = "",
issn = "0095-8956",
doi = "http://dx.doi.org/10.1006/jctb.1997.1767",
url = "http://www.sciencedirect.com/science/article/pii/S0095895697917676",
author = "Artur Andrzejak"
}

@article{honi, 
author = {Winfried Hochst\"attler and Robert Nickel}, 
title = {The Flow Lattice of oriented matroids}, 
journal = {Contributions to Discrete Mathematics}, 
volume = {2},
number = {1},
pages = {68--86},
year = {2007}
}

@article{honijct,
  author    = {Winfried Hochst{\"a}ttler and
               Robert Nickel},
  title     = {On the chromatic number of an oriented matroid},
  journal   = {J. Comb. Theory, Ser. B},
  volume    = {98},
  number    = {4},
  year      = {2008},
  pages     = {698-706},
  ee        = {http://dx.doi.org/10.1016/j.jctb.2007.10.004},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}
@article{honese,
 author = {Winfried Hochst\"{a}ttler and Jaroslav Ne\v{s}et\v{r}il},
 title = {Antisymmetric flows in matroids},
 journal = {Eur. J. Comb.},
 volume = 27,
 number = 7,
 year = 2006,
 issn = {0195-6698},
 pages = {1129--1134},
 doi = {http://dx.doi.org/10.1016/j.ecj.2006.06.018},
 publisher = {Academic Press Ltd.},
 address = {London, UK, UK},
 }

@book {om,
    AUTHOR = {Bj{\"o}rner, Anders and Las Vergnas, Michel and Sturmfels,
              Bernd and White, Neil and Ziegler, G{\"u}nter M.},
     TITLE = {Oriented matroids},
 PUBLISHER = {Cambridge University Press},
   ADDRESS = {Cambridge},
      YEAR = {1999},
   EDITION = {2nd},
     PAGES = {xii+548},
}

@article{folklaw, 
  author = {Folkman, Jon and Lawrence, Jim},
  title = {Oriented matroids},
  journal = {Journal of Combinatorial Theory. Series B},
  volume = {25},
  year = {1978},
  number = {2},
  pages = {199--236}
}

@article{ bland:orientability,
author = {Robert G. Bland and Michel Las Vergnas},
title = {Orientability of matroids},
journal = {Journal of Combinatorial Theory Series B},
volume = {23},
year = {1978},
pages = {94--123},
publisher = {Academic Press, Inc.},
}

@book {oxley,
    AUTHOR = {Oxley, James G.},
     TITLE = {Matroid theory},
 PUBLISHER = {The Clarendon Press Oxford University Press},
   ADDRESS = {New York},
      YEAR = {1992},
     PAGES = {xii+532},
}

@book {diestel,
	edition = {3rd},
	title = {Graph Theory},
	isbn = {3540261834},
	publisher = {Springer},
	author = {Reinhard Diestel},
	month = feb,
	year = {2006}
}

@article{crapo_tutte_1969,
	title = {The Tutte polynomial},
	volume = {3},
	url = {http://dx.doi.org/10.1007/BF01817448},
	doi = {{10.1007/BF01817448}},
	number = {3},
	journal = {Aequationes Mathematicae},
	author = {Henry H. Crapo},
	month = oct,
	year = {1969},
	pages = {314}
}

@inproceedings{tutte3,
author = "W.T. Tutte",
title = "A geometrical Version of the Four Color Problem", 
booktitle =  "Combinatorial Math. and Its Applications",
editor = "R. C. Bose and T. A. Dowling",
year = "1967",
organization = "Chapel Hill, NC: University of North Carolina Press"
}


@article{tutte2,
title = "On the algebraic theory of graph colorings",
journal = "Journal of Combinatorial Theory",
volume = "1",
number = "1",
pages = "15 - 50",
year = "1966",
note = "",
issn = "0021-9800",
doi = "DOI: 10.1016/S0021-9800(66)80004-2",
url = "http://www.sciencedirect.com/science/article/B8JGW-4PYS996-4/2/e36baec1b79a4973f0b17d753003fd8c",
author = "W.T. Tutte"
}
@mastersthesis{Kilpatrick,
	title = {Tutte's first colour-cycle conjecture.},
	author = {Kilpatrick, Peter Allan},
	year = {1975},
	keywords = {Mathematics and Applied Mathematics.},
	school = {University of Cape Town}
}
@article {SeymourNZ6,
    AUTHOR = {Seymour, P. D.},
     TITLE = {Nowhere-zero {$6$}-flows},
   JOURNAL = {J. Combin. Theory Ser. B},
  FJOURNAL = {Journal of Combinatorial Theory. Series B},
    VOLUME = 30,
      YEAR = 1981,
    NUMBER = 2,
     PAGES = {130--135},
      ISSN = {0095-8956},
     CODEN = {JCBTB8},
   MRCLASS = {05C38 (05C20 90B10)},
  MRNUMBER = {MR615308 (82j:05079)},
MRREVIEWER = {Fran{\c{c}}ois Jaeger},
}

@article{Jaeger,
title = "Flows and generalized coloring theorems in graphs",
journal = "Journal of Combinatorial Theory, Series B",
volume = "26",
number = "2",
pages = "205 - 216",
year = "1979",
note = "",
issn = "0095-8956",
doi = "DOI: 10.1016/0095-8956(79)90057-1",
url = "http://www.sciencedirect.com/science/article/B6WHT-4D7K884-RV/2/90bb1ef3c2489c46afdb26e62f1d581c",
author = "F. Jaeger"
}

@Article{Tutte:dichromate,
  author = 	 {W.T. Tutte},
  title = 	 {A contribution to the theory of chromatic polynomials},
  journal = 	 {Canad. J. Math.},
  year = 	 {1954},
  volume = 	 {6},
  pages = 	 {80-91},
}

@Article{Tutte:Abelian,
  author = 	 {W.T. Tutte},
  title = 	 {A class of Abelian groups},
  journal = 	 {Canad. J. Math.},
  year = 	 {1956},
  volume = 	 {8},
  pages = 	 {13-28},
}

@article{robertson_four-colour_1997,
	title = {The {Four-Colour} Theorem},
	volume = {70},
	issn = {0095-8956},
	number = {1},
	journal = {Journal of Combinatorial Theory, Series B},
	author = {Neil Robertson and Daniel Sanders and Paul Seymour and Robin Thomas},
	month = may,
	year = {1997},
	pages = {2--44}
}

@article{appel_every_1976,
	title = {Every planar map is four colorable},
	journal = {Bull. Amer. Math. Soc.},
        volume = 82, 
        number = 5, 
	author = {Kenneth I. Appel and Wolfgang Haken},
	year = 1976,
	pages = {711-712}
}

@article{wagner_ber_1937,
	title = {{\"Uber eine Eigenschaft der ebenen Komplexe}},
	volume = 114,
	url = {http://dx.doi.org/10.1007/BF01594196},
	doi = {{10.1007/BF01594196}},
	number = 1,
	journal = {Mathematische Annalen},
	author = {K. Wagner},
	month = dec,
	year = 1937,
	pages = {570--590}
}

@ARTICLE{Hadwiger,
    author = {Hugo Hadwiger},
    title = {{\"Uber eine Klassifikation der Streckenkomplexe}},
    journal = {Vierteljahresschrift der Naturforschenden Gesellschaft in Z\"urich},
    year = 1943,
    volume = 88,
    pages = {133--142}
}
@ARTICLE{RST,
    author = {Neil Robertson and Paul Seymour and Robin Thomas},
    title = {Hadwiger's conjecture for $K_6$-free graphs},
    journal = {Combinatorica},
    year = {1993},
    volume = {13},
    pages = {279--361}
}
@article{wang_nowhere-zero_2009,
	title = {Nowhere-zero 4-flow in almost Petersen-minor free graphs},
	volume = {309},
	issn = {{0012-365X}},
	url = {http://www.sciencedirect.com/science/article/B6V00-4RGFYG8-2/2/54ac0c6793127a1cdc43bef6181ad79e},
	doi = {10.1016/j.disc.2007.11.055},
	number = {5},
	journal = {Discrete Mathematics},
	author = {Xiaofeng Wang and {Cun-Quan} Zhang and Taoye Zhang},
	month = mar,
	year = {2009},
	keywords = {4-flow, Almost Petersen-minor free graphs, Edge-3-coloring, Integer flow, Petersen minor},
	pages = {1025--1032}
},

@article{lai_nowhere_2005,
	title = {Nowhere zero 4-flow in regular matroids},
	volume = {49},
	url = {http://portal.acm.org/citation.cfm?id=1384486},
	abstract = {Jensen and Toft [8] conjectured that every 2-edge-connected graph without a K5-minor has a nowhere zero 4-flow. Walton and Welsh [19] proved that if a coloopless regular matroid M does not have a minor in {{M(K3,3),} {M*(K5)},} then M admits a nowhere zero 4-flow. In this note, we prove that if a coloopless regular matroid M does not have a minor in {{M(K5),} {M*(K5)},} then M admits a nowhere zero 4-flow. Our result implies the Jensen and Toft conjecture. © 2005 Wiley Periodicals, Inc. J Graph Theory},
	number = {3},
	journal = {J. Graph Theory},
	author = {{Hong-Jian} Lai and Xiangwen Li and Hoifung Poon},
	year = {2005},
	keywords = {excluded-minors, nowhere zero flows, regular matroids cycle covers},
	pages = {196--204}
}

@book{white_combinatorial_1987,
	title = {Combinatorial Geometries},
	isbn = {0521333393},
	lccn = {0095},
	publisher = {Cambridge University Press},
	author = {White, Neil},
	month = sep,
	year = {1987}
}


@article{arrowsmith_enumeration_1982,
	title = {On the enumeration of chains in regular chain-groups},
	volume = {32},
	issn = {0095-8956},
	lccn = {0009},
	url = {http://www.sciencedirect.com/science/article/pii/0095895682900788},
	doi = {10.1016/0095-8956(82)90078-8},
	number = {1},
	journal = {Journal of Combinatorial Theory, Series B},
	author = {Arrowsmith, {D.K} and Jaeger, F},
	month = feb,
	year = {1982},
	pages = {75--89},
}

@article {matroiddecomposition,
    AUTHOR = {Seymour, P. D.},
     TITLE = {Decomposition of regular matroids},
   JOURNAL = {J. Combin. Theory Ser. B},
  FJOURNAL = {Journal of Combinatorial Theory. Series B},
    VOLUME = {28},
      YEAR = {1980},
    NUMBER = {3},
     PAGES = {305--359},
      ISSN = {0095-8956},
     CODEN = {JCBTB8},
   MRCLASS = {05B35 (05C50)},
  MRNUMBER = {579077 (82j:05046)},
MRREVIEWER = {Thomas Brylawski},
       DOI = {10.1016/0095-8956(80)90075-1},
       URL = {http://dx.doi.org/10.1016/0095-8956(80)90075-1},
}


@article{hochstattler_joins_2011,
	title = {Joins of oriented matroids},
	volume = {32},
	issn = {0195-6698},
	lccn = {0000},
	url = {http://www.sciencedirect.com/science/article/pii/S0195669811000345},
	doi = {10.1016/j.ejc.2011.02.005},
	abstract = {We define series/parallel/2-sum connections of two oriented matroids in terms of various axiom systems and an oriented modular join and sum operation by means of signed cocircuits and covectors.},
	number = {6},
	journal = {European Journal of Combinatorics},
	author = {Hochstättler, Winfried and Nickel, Robert},
	month = aug,
	year = {2011},
	pages = {841--852},
}


@book{Schrijver,
	title = {Theory of Linear and Integer Programming},
	isbn = {0471982326},
	lccn = {4998},
	publisher = {Wiley},
	author = {Schrijver, Alexander},
	month = jun,
	year = {1998}
}