Well, I don't expect a Jewish source to concede what Trinitarian Christians believe about Jehovah. Their scriptures, and ours' of course, say otherwise. Take, for example, the "Shamah" of Deuteronomy 6:4
Hear O Israel: The LORD our God is one Lord.
shama` Yisra'el Yĕhovah 'elohiym 'echad Yĕhovah
The word "echad" has the meaning of joined in one, together, as a fist is composed of fingers drawn together.
There are also many verses where Jehovah proclaims that apart from him there is no savior, he alone is the savior and, also, that he is the alpha and omega, the first and last - terms used by and for Jesus in the New Testament. Who you gonna believe???
Point taken. But remember that these verses were written a thousand and a half years before Christ and the Jews thought that they had the meaning down pat.
Pious Jews think that we are crazy with this three in one thing.