Ronconi, M. Cristina: 
A Regular Threefold of General Type with $p_{g} = 0$ and $P_{2} = 6$
 Bollettino dell'Unione Matematica Italiana Serie 9 2 (2009), fasc. n.3, p. 607-621,  (English)
pdf (200 Kb), djvu (158 Kb).  | MR 2569294  | Zbl 1184.14069 
Sunto
The range of the bigenus $P_{2}$ is one of the unsolved problems concerning smooth complex projective regular threefolds of general type with $p_{g} = 0$: The examples in the literature have $P_{2} \le 5$. In the present paper we present a non-singular threefold with $p_{g} = q_{1} = q_{2} = 0$; $P_{2} = 6$; the bicanonical map is stably birational.
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