ALM REST API 12.20 getting requirement traceability information.

Hi,

I'm trying to get requirement traceability information thought the REST API. But I can't find any way to get the ids of trace-to and trace-from of Requirement.
For example, ReqA(id=200) have a trace to ReqB(id=201) when I retrieve the information of ReqA(id=200) , I need to know trace-to id (201). What should I do to get this traceability information?

Thanks,