Page 109 - Principles of Canoeing
Ray Goodwin's 2011 publication, Canoeing, has an step by step photo sequence of the tying method on pages 170-171. These pages are available for preview here (*pdf format). I've used this method before (see poling daytrip post here) but find tying and untying a little cumbersome so often leave the towing bridle attached with the rope in the canoe until the next opportunity for lining / tracking arises.
Recently, I stumbled across a scanned digital edition of Field and Stream (April 1933 Vol. 37 No. 12 ). Page 70 had a tiny article with an illustration with a different method. This one involves a simple slip-knot and a paddle for tension to form an alternate bridle method. Here's the brief clipping...
Since I've never seen this method before, I posted a thread about it over on the CanoeTripping.net forums to get some feedback from more experienced trippers. There are a few responses from folks who give it a thumbs up. Hoping to try this out for myself next season and will report back.