Changes
<ref name="Se">A. Sebő, ''Hilbert bases, Carathéodory’s theorem and combinatorial optimization'', in: R. Kannan, W.R. Pulleyblank (Eds.), Integer Programming and Combinatorial Optimization, Univ. of Waterloo Press, Waterloo, Canada, 1990, pp. 431–455, [http://www.g-scop.inpg.fr/~seboa/sebo_files/papers/hb00ipco.ps Author link]</ref>
<ref name="Br">W. Bruns, J. Gubeladze, M. Henk, A. Martin, R. Weismantel, ''A counterexample to an integer analogue of Carathéodory’s theorem'', J. Reine Angew. Math. 510 (1999) 179–185. [http://dx.doi.org/10.1515/crll.1999.045 DOI link], [http://page.mi.fu-berlin.de/lapinou/lehre/bghmw.pdf Author link]</ref>
<ref name="Pa">J. Pap, ''Recognizing conic TDI systems is hard'', [http://dx.doi.org/10.1007/s10107-009-0294-5 DOI link]</ref>
