6INGENSAND H. The Evolution of Digital Levelling Techiques-Limitations and Solutions [ EB/OL ].http://www. ddg. org/. 被引量:1
7WOSCHITZ H, BRUNNER F K. System Calibration of Digital Levels-Experimental Results of Systematic Effects [ EB/OL]. http://www. cis. tugraz. at/. 被引量:1