Source: Dr. Mary J. McGlasson, https://www.youtube.com/watch?v=SmOMp8gycMA&list=PLF2A3693D8481F442&index=16;
https://www.youtube.com/watch?v=cwBpq5T0ks0&list=PLF2A3693D8481F442&index=17;
and https://www.youtube.com/watch?v=29S7FzI7s7g&list=PLF2A3693D8481F442&index=21
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