[1]B. Lickfett и F. Partmann, PMI, т. 174, сс. 101-102, мар. 2008.

[1]B. Lickfett and F. Partmann, "Determination of Accuracy of a Combined System of Tachymeter and Echo-Sounder and Suggestions of Improvement", PMI, vol. 174, pp. 101-102, Mar. 2008.