Can someone provide some resources (books, notes, articles etc.) on Gravitational Soliton (specially on the Belinski–Zakharov transform)?

I've found only the following two reference from the Wikipedia references:

1. Belinskii, V.; Zakharov, V. $(1978)$. "Integration of the Einstein Equations by Means of the Inverse Scattering Problem Technique and Construction of Exact Soliton Solutions". Sov. Phys. JETP. $48~(6):~985–994$. ISSN $0038-5646$.
2. Belinski, V.; Verdaguer, E. ($2001$). Gravitational Solitons. Cambridge Monographs on Mathematical Physics.

I'm searching for a few more.

NOTE: Wikipedia is saying,

The Belinski–Zakharov (inverse) transform is a nonlinear transformation that generates new exact solutions of the vacuum Einstein's field equation. It was developed by Vladimir Belinski and Vladimir Zakharov in $1978$.$^{[1]}$ The Belinski–Zakharov transform is a generalization of the inverse scattering transform. The solutions produced by this transform are called gravitational solitons (gravisolitons).