If the wall is made of plasterboard, fixing on her bookshelf refrain. She could not withstand the weight of the books. If the room has a wall of a different material, use it, if not, give preference to the book closet.
On wood wall hang book shelf in the following way. Using a tape measure, measure the distance between the centers of the mounting holes of the shelf. Using the building level (conventional or laser), draw on the wall at the desired height a horizontal line. Then mark on this line of the location of the screws. The distance between them must be exactly equal to the measured. Head screws with a length of several inches and tighten with a screwdriver to a depth equal to about 4/5 of the length. Cap screws must be directed slightly upwards.
For hanging shelves on a concrete wall first, make a layout as described above. Then ask the seller a hardware store to pick up screws, dowels and a drill so that they fit to each other. Before drilling with the help of finder flush make sure that you will not get a drill to the cable. Drilling exercise slightly at an angle so that the cap screws in this case was directed slightly upwards. Insert the hole plugs on the depth, and screws in any screw approximately 4/5 of the length.
Hanging book shelf, load it with books and leave for the day. Then, having unloaded and removing the shelf, make sure that the screws are still holding tight. Then set the shelf back on and load again.
Observe special caution when working with shelf with sliding glass. In the process of hanging they can fall out of the guides. To avoid this, carefully remove them and after installation re-insert shelves. Never overload the shelf, placing extra books and other items (such as vases or statues) on her top lid.