"(33)"
If we substitute this in the second of the formula (31), we get, remembering (23),
"(34)"
By substituting the right-hand side of (34) in (29), we get
"(29a)"
Divergence of the contravariant four-vector.
Let us multiply (26) with the contravariant fundamental tensor gμν (inner multiplication), then by a transformation of the first member, the right-hand side takes the form
