Scotlandsplaces website

Editor, Greetings again!
I am struggling with a citation model for the Scotlandsplaces website. The databases on this website are various. I am using placenames A-Z for various farmsteads in the parish of Old Deer, Aberdeenshire. For example: Slampton farmstead. The citiation model I have created is:

National Archives of Scotland, " Ordinance Survey Name Books, 1865-1871," database, ( accessed 10 August 2015), entry for Slampton, parish of Old Deer, Aberdeenshire; citing OS1/1/68/139.

This is my first effort. The citing portion at the end is troublesome as I am not sure what exactly to refer to besides the book, volume, page data. Help Please! Teresa Mills