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In the library where is worked in the 1970s there was a story that three floors of books would protect the people under them from cosmic rays.

But later was said to be not good enough.

One segment:
An extremely thick, multi-story structure made of books would be necessary to offer any significant protection from gamma rays from space, making it an impractical solution. It is virtually impossible to provide complete protection, as highly energetic gamma rays are extremely penetrating.

Unlike concrete, books are made of paper, which is a low-density, low-atomic-number material, inefficient at absorbing gamma rays, allowing most of the radiation to pass through with minimal interaction.

Materials rich in hydrogen, like water and plastics (or, in this case, paper) are more effective at slowing down these neutrons, which can also be harmful. However, the primary cosmic rays themselves are so energetic that a thick shield of any material is needed. ...you need roughly 2.4 times the thickness of books as you would concrete of books.

A single floor is typically 10 to 12 feet high. So, protecting against “typical” gamma rays would require more than one full floor of books. However, gamma rays from space can have much higher energy levels, which would require significantly thicker shielding to stop effectively.