upload sample file to FIG. 2.7
upload sample file to FIG. 2.15
upload sample file to FIG. 3.2
upload sample file to FIG. 3.5
upload sample file to FIG. 3.9
upload sample file to FIG. 3.11
upload sample file to FIG. 3.14
upload sample file to FIG. 3.18
upload sample file to FIG. 4.7