Let be a polarized surface and let : be the blow-up at points . . . , on . Set , where are positive integers and are the (-1)-curves over . We consider whether is ample or not if are in a general position. The cases of sectional genus two are studied especially precisely.
Koji YOKOYAMA. "On blowing-up of polarized surfaces." J. Math. Soc. Japan 51 (3) 523 - 533, July, 1999. https://doi.org/10.2969/jmsj/05130523