I think they were in the old AISC "Blue Book", 7th Edition.  I have an old catalogue from Bethlehem Steel that has several "carbuilding" Z's sized CZ13 and some other smaller Zees, Z4 and Z3.  Are those the sizes you're interested in?

"Z' shapes have been used for steel sheeting in the trenching industry. Most good steel companies can locate them for you. US Steel made them also. The last ones I bought were from a Steel Co. in St. Louis, Mo.

I'm assuming you are referring to a light gage Z section.

Z-section properties are published in AISI's Cold Formed Steel Design Manual for many common sections (along with hat sections, channels, and more). One caveat: many of these sections are proprietary, so there may not be published information for your specified shape. You may have to contact the manufacturer, if possible.
 
There is another solution, however. If the specific shape you are looking for isn't listed, methods are presented for calculating the properties based on the section geometry (I'd recommend measuring the section in the field with calipers). The analysis is quite rigorous and time-consuming, and accounts for the "effective" section modulus. Not accounting for the effective section modulus generally results in overestimating section strength by between 5% and 10%.