KROUPA M., KALAČ P., DRBAL K. (1980): The variability of the contents of trace elements in some edible mushrooms. Česká Mykologie 34(1): 9-12 (published: 1980)
DRBAL K., KALAČ P. (1976): Content of cobalt in some edible mushrooms. Česká Mykologie 30(1): 24-26 (published: 1976)
DRBAL K., KALAČ P., ŠEFLOVÁ A., ŠEFL J. (1975): Content of copper in some edible mushrooms. Česká Mykologie 29(3): 184-186 (published: 1975)
DRBAL K., KALAČ P., ŠEFLOVÁ A., ŠEFL J. (1975): Content of the trace elements iron and manganese in some edible mushrooms. Česká Mykologie 29(2): 110-114 (published: 1975)