Go back / go forward: keyboard shortcut?

Could somebody please tell me what the keyboard shortcuts are to go back or forward?

When I switch from an itemlink to an article, I want to be able to switch forward and back, using the keyboard.

BTW: I found out that it sometimes takes 1 click to switch back to the document with the itemlink and sometimes 2 clicks (because it goes to another place within the pdf document first). Any idea how to prevent the extra click?

As always: thanks for your help!

The shortcuts CMD[ and CMD] (also under the Go menu) will navigate back and forward.