New member so hopefully this question is in the appropriate area.
I collect plate, zip and mail early blocks thru 1979. Some time ago I purchased a Harris Plate Block album that had pages through 1975. I have found annual supplements on eBay
for 1976 and 1977. They each contained pages for plate, zip and mail early blocks. I have been looking for supplements for 1978 and 1979 but the few I have found have the "contents" sticker on the front that say only pages for regular and air mail plate blocks are contained. Earlier supplements said regular and air mail plate blocks, zip blocks and mail early/emblem blocks.
My question is what Harris supplement includes the pages for the zip and mail early blocks?
Thanks for your help.