Suppose we are given two integer numbers $p$ and $q$ such that $p+q\equiv 0 \pmod{12}$. There is a result saying that for every such pair there exists a non necessarily connected almost complex manifold of dimension $4$ such that its Chern numbers are equal to $p$ and $q$. Could you give me a reference for the proof of this result?



Chern numbers of almost complex manifolds
A. Van de Ven: [**On the Chern numbers of certain complex and almost complex manifolds**](http://dx.doi.org/10.1073/pnas.55.6.1624), *Proc. Natl. Acad. Sci. USA* **55**, 1624-1627 (1966). [ZBL0144.21003](https://zbmath.org/?q=an:0144.21003).


