In some industries, like payday loans for example, it is hard to get legitimate citations.

If somehow a well discussed technology runs close to your core field it may be worth creating content around that linking opportunity and ask the right people for feedback on your end produt. Many of them will give your site authoritative links that are going to be hard to compete with.

Even run of the mill online flower shops may go from a me too site to a heavily linked industry authority if they added something like this to their sites. As storage costs go down and more people filter information in more and more ways there become more and more marketing opportunities. Largely because there become more overlapping intersections between industries. Many of those intersections get talked about and heavily linked at.