In the mid 1970s articles dealing with Post Offices in the Northwest Territories and the Yukon were published in the
Canadian Philatelist, journal of the Royal Canadian Philatelic Society.
Northwest Territories
Thompson, K.
Northwest Territories, Checklist of Modern Postmarks, Canadian Philatelist (1974) Vol.25 No.5 p.276
http://www.rpsc.org/CP_scans/Canadi...o.%20144.pdfYukon Territory
Smith, F.C.,
Yukon Territory: Current Postal MarkingsCanadian Philatelist (1976) Vol.27 No.2 p.79
http://www.rpsc.org/CP_scans/Canadi...o.%20153.pdfI would recommend membership in the Canadian Postal History Society. Their study group dealing with Northern Post Offices would be most informative.
http://www.postalhistorycanada.net/...ps/Northern/I expect there will be disagreement from some posters with respect to my next comment. I appreciate that you are sending covers to post offices to receive postmarks. I do this as well and purchase these "favour" covers. In some cases this is the only way postmarks can be obtained. Instead of using out-of-period commemoratives, I prefer using current definitive stamps. The Victoria stamp on your cover is a distraction, taking away from the postmark. Just an opinion.
You might want to write to businesses in the North and ask them if they might have envelopes to send you. You never know.
I note that the cover you posted was cancelled in 2001 so you have been at this for a while. You can probably provide us with information.