Radial velocity differences, Δ RV, between rotational transitions of different molecules and the NH₃(1, 1) inversion line for the sources observed at the Effelsberg 100-m telescope (2011–2013). 1σ statistical errors are indicated. The coordinate offsets in arcsec are given in parentheses. Filled circles are for data from this paper; open triangle, square, and circle are for data from Papers I and II.