Are these real?

I have had two autographed cards in my possession for a long time. I bought them both from the same dealer at the same card show back when I was a teenager.

This was before the huge boom in autograph collecting, which gave rise to all the forgeries that now flood the market. There were no accompanying authentication letters or stickers or anything like that with the two cards.

But even though there was a little more trust back in those days, there is still doubt regarding what I own. I have no idea whether the Harmon Killebrew card (up top) or the Sandy Koufax card (down below) were autographed by the actual players.

Every image that I have been able to find on the intertubes seems to match these two autographs. But I'm not very well versed on what to look for or what other avenues there are for determining if your autograph is the real thing.

So I ask those who collect autographs regularly and have experience in varifying such autos: what do you think? Do these look legit to you?

Again, I think they're the real thing. But I'm sick of dealing with that nagging feeling of doubt. I'd like to put it to rest.