و آر ایل:https://ohiostate.pressbooks.pub/app/uploads/sites/95/2018/01/Methane-Hydrate-around-Japan-Map_WikiCommons-300x300.png
و آر ایل:https://ohiostate.pressbooks.pub/sciencebitesvolume2/chapter/5-1-japans-environmental-challenges-and-energy-future/
