This pdf isn't accurate, at least it's not accurate for Iz's version. For example, Iz clearly plays C, Em, F, C, and not C, G, F, and C, at the opening.

Try both on the uke and see for yourself.

Here's the beginning of a better arrangement I found. (I wish I could remember where I downloaded this arrangement...)

C Em
Somewhere over the rainbow

F C
way up high

F C
There's a land that I heard of

G Am F
once in a lullaby...

The introduction from the version I found is also (fairly) accurate:

C,Em,F,Fadd9,C,Em,F,Fadd9,F,F,C,Em,F,C,F,G,C, Fadd9…

-=-Joe