Does anyone know a serious provider for online therapy?

I read about a study that showed good results in internet-based therapy for complicated grief and PTSD.

So far, I couldn´t find a study to participate in.

I found some online therapy, but I don´t know which ones are to be taken seriously.

I know not to trust just any website that will take your money...
but as said, the study showed effective results and in the Netherlands, internet-therapy is even payed by the insurance companies...

I´d be thankful for any information about internet therapy for PTSD/complicated grief.