General Relativity: An Introduction for Physicists · Problem 11.17
Schwarzschild black holes — Hobson, Efstathiou & Lasenby
Physics · einstein-rosen-wormhole-embedding
Problem
Perform an embedding into three-dimensional Euclidean space of the 2-space with line element
dσ2=dr2+(r2+a2)dϕ2,
and hence show that the resulting 2-surface has a geometry reminiscent of a wormhole.