You will note that each corbel has two Hanging strips on the back so that they will hang on the head of a #10 wood screw that  is anchored into wood beam in the wall or if not not available a moly plug  anchored into a sheet rock wall will be sufficent.. Be certain not to overload the shelf so that the stress on the anchors will not cause the moly plug to fail..

 When purchasing check the stress loads for the moly plug that you are using. These range in different load bearing capacities.....