1.   https://april.eecs.umich.edu/media/pdfs/olson2010tags.pdf

2.  https://www.cancer.gov/about-cancer/treatment/types/radiation-therapy/radiation-fact-sheet

3.  http://docs.ros.org/hydro/api/moveit_setup_assistant/html/doc/tutorial.html

4.  http://docs.ros.org/jade/api/moveit_commander/html/classmoveit_
   commander_1_move_group_1MoveGroupCommander.html

5. http://docs.ros.org/indigo/api/moveit_$tutorials/html/doc/pr2_tutorials/planning/
   scripts/doc/move_group_python_interfac_tutorial.html

6. http://people.csail.mit.edu/kaess/apriltags/

7. https://github.com/ros-drivers/usb_cam

8. https://github.com/RIVeR-Lab/apriltags_ros

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