I heard this example was given in Whitehead's paper A CERTAIN OPEN MANIFOLD WHOSE GROUP IS UNITY.( http://qjmath.oxfordjournals.org/content/os-6/1/268.full.pdf ) But I was confused by his term. Thus I'm looking for an explanation in more standard terms about this example.

But since my aim is to know about an example of this kind, any alternative will do either.