So I know the basics of Wick's theorem, but unsure about how to solve this time ordered product of a term that involves normal ordering. Is it just simply the sum of all possible contractions, but no self contractions?

Any hints on what to do would be appreciated.

$$\frac{-i \lambda}{(2!)^2} \int d^4x \langle0|T \left( \phi^\dagger (1) \phi(2) \phi^\dagger(3) \phi(4) : (\phi^\dagger(x) \phi(x) )^2 : \right)|0\rangle.$$

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    $\begingroup$ Please use MathJax on this site instead of posting the images. $\endgroup$ – exp ikx Feb 6 at 17:24

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