I. Dimitrov, Zheljazkov, V. D., and Zhalnov, I.,
“Productivity of soybean cultivars and their effect on soil fertility”,
Higher Institute of Agriculture – Plovdiv, Scientific Works, vol. 4, pp. 91-94, 1995.
I. Dimitrov, Zheljazkov, V. D., Janchev, I., and Terziev, Z.,
“Photosynthetic productivity in a ribbon sowing of maize and soybean”,
Higher Institute of Agriculture – Plovdiv, Scientific Works, vol. 36, pp. 73-79, 1991.
I. Dimitrov, Terziev, Z., Zheljazkov, V. D., and Janchev, I.,
“Effect of fertilization and planting density on the productivity of maize hybrids grown under water stress. ”,
Higher Institute of Agriculture – Plovdiv, Scientific Works, vol. 36, pp. 67-71, 1991.
V. D. Zheljazkov, Topalov, V., Yankov, B., Terziev, J., and Dimitrov, I.,
“Changes in the quality of Mentha rhizome as depending on the time of overground mass harvesting and the method of weed control”,
Higher Institute of Agriculture – Plovdiv, Scientific Works, vol. 37, pp. 239-247, 1992.