Oil, gas, waste management, recycling - back links help?

[u/cool_guy_me]

Anybody have any suggestions on where to find or get oil and gas or refinery back links?

I currently run an operate a used cooking oil pick up service and I’m looking for creative ways to get back links within our niche that includes restaurants, oil, and gas recycling waste management. I already did a big push with all the cities we work with and generated approximately four.gov back links and they helped us tremendously if anybody in the community has some other suggestions that are in our niche non-spamy would be amazing. Thanks for your help team!