It's the "objective" lens ... the big one in the front.
I'm pretty sure there is only one element named after Mendeleev: <span>Mendelevium.</span>
Answer
The moveable parts of the pop up book are of often cut out by hand and are folded and glued by hand upon the printed pages. The cover is glued or sewn to the lining. Front and backs are often made up from board, which is just a heavier gauge paper than is used for the pages.
Explanation
Hope that this helps you and have a great day:)
As BBC ztrrtv B 4 C w.a)z
