Although it is incomplete, this survey alone would make it very easy to establish that the major references of the Vajra Bridge are absolutely not the tantras listed by Longchenpa as being the fundamental tantras of the Klong sde. Of course, the investigation would have to be deepened and systematized; but it is already obvious that this can only be explained in two ways:
Either there have been other systems of Klong sde practice, of which the rDo rje zam pa is only one form that has been preserved by who knows what chance;
Or Longchenpa - or the authors whose opinions he reproduces - had only a weak and indirect knowledge of Klong sde.
Both hypotheses potentially have serious consequences.
Kun tu bzang po che ba rang la gnas pa’i rgyud : pp. 277, 341
Kun byed rgyal po : p. 39
Kun bzang rdo rje : author of the developed rDo rje zam pa: pp. 16, 303 (so he is not the author of this text, but a master of the lineage, perhaps the author's master - according to the colophon, p. 334, the author is master Ye shes seng ge, writing according to the instructions of this master)
Klong dgu : pp. 19, 332
bKa’ samanta nam mkha’ dang mnyam pa [bde ba kun du spyod pa]’i rgyud : pp. 16, 332
dGyes pa rdo rje : p. 326
rGyud bla ma : pp. 38, 284
Nges brjod bla ma’i lung : p. 32
Chos spyod thams cad kyi man ngag mngon par rtogs pa’i rgyud : p. 258