Lickfett , Britta, и Friedrich Partmann. 2008. Записки Горного института 174 (март), 101-2. https://pmi.spmi.ru/pmi/article/view/7495.

Lickfett , Britta, and Friedrich Partmann. 2008. "Determination of Accuracy of a Combined System of Tachymeter and Echo-Sounder and Suggestions of Improvement". Journal of Mining Institute 174 (March), 101-2. https://pmi.spmi.ru/pmi/article/view/7495.