The bookselves usually are made of wood (melamine) and divided into open bookselves, with doors below, full doors, doors below and glass upper.
Usually the width is 80-90 cm (80cm is the preferred so the selves to not make any "belly" from the weight) or 40cm when we have not enough room.
The heights starts from 80 cm, 120 cm, 160 cm, 180 cm and 195 cm,
The depth is usually between 35 - 40 cm
At the bottom should be better placed regulators for better stand of the selves.
In the back of the bookselves should be placed 8 mm thickness melamine and avoid cardboard because the resistance reduced dramatically during the use.
The shelves should have adjustable heights to achieve better implementation of the items that we want to place in them.
There are also bookselves that made of plastic or metal shelves.