For another interesting (but non-canonical) presentation of what Archbishop Lefebvre and Canon Hesse had to say about attendance at the NOM, I recommend:
http://tradcatknight.blogspot.ca/2016/10/new-mass-is-valid-therefore-i-can-go.html
Fighting to Maintain the Catholic Faith Whole and Inviolate and the Line of Archbishop Marcel Lefebvre under the Pontificate of Benedict XVI
For another interesting (but non-canonical) presentation of what Archbishop Lefebvre and Canon Hesse had to say about attendance at the NOM, I recommend:
http://tradcatknight.blogspot.ca/2016/10/new-mass-is-valid-therefore-i-can-go.html