In article , news
writes:

The redshift-distance and velocity-distance
laws
You say we should read Harrison's article,

It is one of the best on the topic.

but what can you really
learn from a verbose article like this?

A wealth of information.

What are we to make of an equation for the distance to a co-moving
body where the units are so far out of balance: (where c must be the
speed of light R is dimensionless)
L = cR_0*r meters? section 6.2

Some authors have the scale factor dimensionless. Others prefer it to
have a dimension and express "distance" via a dimensionless quantity,
which has the advantage that such comoving distances do not change when
the universe expands (the physical distance is the coordinate distance
times the scale factor). However, you can be sure that Harrison's
treatment is consistent and that he has not made a simple error such as
an equation where the dimensions don't match.