GREGA, Libor. Vertical integration as a factor of competitiveness of agriculture. In Agricultural economics : an international journal = mezinárodní vědecký časopis. - Prague : Institute of Agricultural and Food Information, 2003. ISSN 0139-570X, 2003, vol. 49, no. 11, s. 520-525. Dostupné na : <http://www.agriculturejournals.cz/publicFiles/59482.pdf>