How to avoid circular reference dependency in Angular4

I have two services.
First one is DataService, which is used to to requests to API.
Second one is AuthService, which does request to identity server and saves access_token.

I need to have DataService inside of AuthService so I can do the request.
I need to have AuthService inside of DataService, to append access_token for authorized access.

How can I resolve this circular dependency, without writing new "data service" class just for AuthService?