The sixth volume of the series has been published. It is Donald J. Mastronarde, Preliminary Studies on the Scholia to Euripides.
As usual the print-on-demand paperback is available at our own sales page and will be available in a few weeks from various online retailers. A version in ePub format will probably be available in the near future. The entire book can be read in open-access page view now, while the book itself (as PDF) will be downloadable after 24 months.
For more about the book and for links to read it or buy it, see our Catalog page.
Update December 19, 2017: the ePub format is now available.