Is selenium toning the only option?

[Jerry Bodine]

Another source to check out is Way Beyond Monochrome, by Ralph Lambrecht and Chris Woodhouse. ...

Agreed, Peter, but it should be noted that the current 2nd Edition is the version to seek.

[Drew Wiley]

Very few "collectible" silver-gelatin prints are actually toned heavily enough to alter all the susceptible silver. If you're worried about that, never collect an Ansel Adam's or Brett Weston or Minor White print (or just about anyone else I can think of). Most of us use toners for the relative improvement in permanence they provide, but more for how they alter image color and DMax. I mostly use gold chloride to cool image tone, selenium, and sulfide brown, sometimes combined for split toning effects. Back in the 19th C, horrible urban pollution due to coal, along with improper fixing and acidic paper pulp mounting affected silver emulsion permanence.