A Few Last Bits I Can't Seem To Identify

On this first one I am having trouble finding the top airmail stamp from Argentina in Scott. The lower one is Scott #B54:



On this Australian airmail stamp there are 2 issues. One in 1949, which is Scott #C6 and then it was issued again in 1956 it seems under Scott #C7. It seems the difference is the perfs between the 2 issues. Any chance someone might be able to eyeball which one it probably is?



This stamp from the Pitcairn Islands I can't seem to find in Scott:



This stamp from Austria 1972 I can't seem to find in either Scott:



Any help you can give on any of these would be much appreciated.

Many thanks as always... Marc

On your Australian stamps, the C7 do not have any watermarks.

Your 1972 Austrian stamp is Scott # B328 semi-postal, commemorating the Stamp Day.

The Pitcairn Islands stamp is Scott # 97. Not illustrated in the Scott catalogue.

George

The other stamp from Argentina is Scott # CB42, an air post semi-postal stamp.

George

Cheers for all that George. That is a big help. I think the Australian might be C7 as I don't see any watermark at all. Many thanks again. Marc