Reference for the p-adic numbers

Can anyone give me a reference (book or a paper) that introduces the p-adic numbers and their important properties? Also, I would love if that reference contained some not to advanced applications of the p-adic numbers to number theory.

Thank you in advance!

p-adic Numbers, p-adic Analysis, and Zeta-Functions, Neal Koblitz (1984, ISBN 978-0-387-96017-3)
This is a short book. If you wish, you can only read the first chapter with 20 pages.