There are a variety of formats used but plotting velocity versus angular impact parameter is very common as it clearly shows where the discrete measurements lie, they are often not symmetrical. See the bottom left panael of the linked picture and figure 2 in the linked paper for examples.

Since there will usually be several data points on each side, a parameterised curve is often fitted and can be plotted on the same chart.

https://inspirehep.net/record/793409/files/f2.png

http://arxiv.org/abs/1307.6031

Thanks for your answers. Would you please help me to find data of both sides of galaxies?

There are databases like SIMBAD that you can search if you have a particular galaxy in mind, or if you want several examples, looking for papers on surveys might be better.

I think your after the 2D velocity field - this can come from integral field spectroscopy, for example.   I attach a color image of such a velocity field here:

Exactly. But I need data not image. Is there any way to find data? I mean something like this:  

R(Kpc)   V1(Km/s)    V2(Km/s)

1                30                   32

2                70                   70

3.5           150                154

5              180                 184

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I gave you a link previously, repeated here. That paper is based on the sort of data you want although R will be an angular value in milli-arcseconds, converting to kpc needs a figure for the galaxy's distance. That paper doesn't have a table of values, there were too many, but you could contact the authors and request the data. Some similar papers might have tables of data points if there are just a few but you'd have to just look through them I think.

http://arxiv.org/abs/1307.6031

Look in older papers where the authors measured the tilt of the galaxy's spectral line - and give the tabular results.  You need to search out these papers.  Try starting with the review paper mentioned earlier.