I would dig into some Google search results for a few hours. Start with the example above and search "learn anatomy online" which will show you top sites and competitors' ads for sites like kenhub.com. Then broaden your search and use Google's autocomplete results to get ideas for more industries. Start typing "online learning for..." and you'll see suggested searches. Also on the bottom or right side of search results pages, you'll see related searches and "people also searched for" which will continue expanding your search paths. Once you gather a list of sites that fit your criteria you can use a tool like www.spyfu.com to find their main competitors. Set a timer because you can get lost in this kind of research for days!!

I can be of help as I have consulted one of my clients in similar engagement.
Get in touch if you wish to discuss further.

Are you asking in terms of lead generation? As in you are looking for companies in that space? Check out http://www.growthok.com

You can find any type of data along with advanced targeting, contact info, and many more.

Well, the simplest answer is to use Google, because the organic search can be really helpful. But you can also visit such websites as Clutch, GoodFirms, etc, where you can choose required features (location, hourly rate, etc.).

In case you're looking for a healthcare IoT company, let me help so you don’t have to waste your time looking through different directories and freelance-platforms. Here is it: https://r-stylelab.com/services/internet-of-things-app-development/healthcare-iot