toy harmonica: 4 hole - 8 tone for simple kid song
24 hole Asia harmonica - 24 tones in a row, each hole got upper hole and lower hole for mixed same tone
10 hole blues harmonica - 10 holes in a row - blow vs draw to create 20 tones
10 hole semi tone (chromatic) harmonica - 10 holes in a row + a leveler - create 20 tones + the semi-tone inbetween
https://www.youtube.com/watch?v=dT7Pkjts7YA
https://www.youtube.com/watch?v=bPsWxPK9304
https://www.youtube.com/watch?v=C4iV_IGOtaw
https://www.google.com.sg/search?q=why+harmonica+bends&source=lnms&tbm=isch&sa=X&ved=0ahUKEwik0IPGsrbLAhVBGY4KHVCTA_MQ_AUIBygB&biw=1164&bih=608
http://www.hoerl.com/Music/harmon5.html
http://www.harmonicaclub.com/lessons/beginners-lesson
http://www.guitarforum.co.za/other-instruments/harmonicaguitar-interaction/
https://www.google.com.sg/search?q=harmonica+types&biw=1162&bih=608&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi6vI3Ut7bLAhUGco4KHT_UCXgQ_AUIBigB
http://www.harmonicaacademy.com/categories/20101027
http://www.harmonica.com/types-of-harmonica-7325.html
http://www.harmonicalessons.com/recommended_def.html
https://en.wikipedia.org/wiki/Harmonica
https://en.wikipedia.org/wiki/Tremolo_harmonica
https://en.wikipedia.org/wiki/Richter-tuned_harmonica
https://www.youtube.com/watch?v=bghOBRA0z-Y
https://www.youtube.com/watch?v=H5Aphh_2PHU
https://en.wikipedia.org/wiki/Chromatic_harmonica
http://thehub.musiciansfriend.com/folk-instrument-buying-guides/harmonica-buying-guide#specialty
neck holder:
灵韵乐器 GG: (harmonica, erhu, ban, flute)
广州威廉乐器 OO: (guitar, ukulele, violin, celo, guzheng, piano, flue, harmonica, pipe, amp, drum tune, cable)