Using AirDrop, I can transfer PDFs from my iPhone to iPad, but cannot do multiples at a time. How can this be done?

Using AirDrop, I can transfer PDFs from my iPhone to iPad, but cannot do multiples at a time. How can this be done?

When I first started my new iPad, some of my books were transfer, but not all, and none of my PDFs were transferred.

I have been unable to use iTunes.

How can I transfer my books and PDFs from my iPhone to iPad.

Currently, I am on Windows 7, but do not want to transfer from my computer, only from my iPhone to my new iPad.

Thank you,

:-)

Vanessa