Comic PLUM DX vol.1, "DX" here stands for "Deluxe". The precursor for this series is コミックプラム/Comic PLUM which ends at vol.17 the same month (Oct. 2010) this one is released, however, there is no printed date in the cover, just like most digital magazine.
As I described before, PLUM DX first released in digital form and goes physical several months later, eg. this one's corresponding physical ver. is out in Feb. 2012, about 4 months later.
There are several digital versions, this gallery and the one to be replaced are all DLSite edition, which may not compared to DiGiket edition in quality and resolution, more than that, it's got much heavier in censorship, I kinda regret buying this one from DLSite. There is also a DMM edition but coated with DRM format.
info on mugi: http://doujinshi.mugimugi.org/book/386599/
digital ver: http://www.dlsite.com/books/work/=/product_id/BJ007871.html http://www.digiket.com/work/show/_data/ID=ITM0045827/