17.
Bremner J.M.: Nitrogen - total, In: Methods of Soil Analysis, Part 3: Chemical Method, eds. Sparks D.L., Page A.L., Helmke P.A., Loeppert R.H., Soltanpour P.N., Tabatabai M.A., Johnston C.T., Sumner M.E., Madison, Wisconsin, USA, American Society of Agronomy and Soil Science Society of America 1996 1085-1121.