Source for 44a minus red filter

Was reviewing filter information in my copy of "the negative" by AA of course and he has examples of using a 44a (minus red) filter and I thought it might be what I am looking for for capturing spring wheat while still very very green. But alas I cannot find a place to but such a beast. Is there a conversion to something more common in the color correction genre i.e. CC05 etc.?

Tiffen.com still lists the Wratten number gels.

Kodak calls this a "light blue-green" but comparing it's spectrophotometric absorption curve to that of a CC50 Cyan shows the CC filters doesn't nearly approach the blue green cutoff of the 44A filter. (according to "Kodak Filters for Scientific and Technical Users")

Tiffen shows it available as a 100mm gel at:

http://www.tiffen.com/displayproduct.html?tablename=kodakaccessories&itemnum=EK1497221