Hope someone can help with the above please? There are three non-isomorphic trees available on 5 vertices as shown in the graphic. The first tree in the picture can be labelled in 5 ways - which I can see using (n!/(k!(n-k)!)

I am told the second and third can be labelled in 60 ways. Could someone explain how the figure of 60 is arrived at?

Many Thnaks

Blobfish