Fibonacci series

Question

Let a,b,c,d are 4 consecutive numbers of Fibonacci series.

Prove or dis-approve:

 ad-bc= ±1

Answer 1

Let's take a=0,b=1,c=a+b,d=c+b.

ad-bc=0-(a+b)=-1

Comments

It's just one example. I want a rigorous proof.