Florek K., Łukaszewicz J., Perkal J., Steinhaus H., Zubrzycki S. (1951): Sur la liaison et la division des points d’un ensemble fini. Colloquium Mathematicum 2: 282–285.10.4064/cm-2-3-4-282-285
Jacques J., Preda C. (2014): Model-based clustering for multivariate functional data. Computational Statistics & Data Analysis 71: 92–106.10.1016/j.csda.2012.12.004
Jakubus M. (2013): Wybrane zagadnienia z gleboznawstwa i chemii rolnej. Wydanie II rozszerzone i uaktualnione, Poznań, Uniwersytet Przyrodniczy w Poznaniu. [In Polish].
Kruskal J.B. (1956): On the shortest spanning subtree of a graph and the travelling salesman problem. Proceedings of American Mathematical Society 7: 48–50.10.1090/S0002-9939-1956-0078686-7
Ogunniyi J.E., Guo C. Tian X.H., Li H.Y., Zhou Y.X. (2014): The effects of three mineral nitrogen sources and zinc on maize and wheat straw decomposition and soil organic carbon. Journal of Integrative Agriculture 13(12): 2768–2777.
Prim R.C. (1957): Shortest connection networks and some generalizations. Bell System Technical Journal 36: 1389–1401.10.1002/j.1538-7305.1957.tb01515.x
Rezig F.A.M., Elhadi E.A., Abdalla M.R. (2014): Decomposition and nutrient release pattern of wheat (Triticum aestivum) residues under different treatments in desert field conditions of Sudan. Int. J. Recycl. Org. Waste Agricult. 3, 69: DOI 10.1007/s40093-014-0069-8.10.1007/s40093-014-0069-8
Thematic strategy for soil protection. Commission staff working document. Communication from the commission to the council, the European parliament, the European economic and social committee and the committee of the regions. COM (2006)231.