sampling
[youtube https://www.youtube.com/watch?v=AVvGo4m2joM&w=560&h=315]
[youtube https://www.youtube.com/watch?v=mn2zeJFV9lk&w=560&h=315]
[youtube https://www.youtube.com/watch?v=-PfVJ_LqWe4&w=560&h=315]
[youtube https://www.youtube.com/watch?v=LrapRYBO-38&w=560&h=315]
[youtube https://www.youtube.com/watch?v=KktwZvSiXUk&w=560&h=315] [youtube https://www.youtube.com/watch?v=KoC6UV7GvfE&w=560&h=315] [youtube https://www.youtube.com/watch?v=HTv_HeM8Eic&w=560&h=315] [youtube https://www.youtube.com/watch?v=SJ7wEG7VoW0&w=560&h=315]
[youtube https://www.youtube.com/watch?v=I7cpgJmensg&w=560&h=315]
[youtube https://www.youtube.com/watch?v=OgpZWVFdoWQ&w=560&h=315]