Serbia Postcard With Stamp And Stationery.

Serbia postcard 1904. Require the following info;
1) What is the overprint?
2) The yellow stains on the stamp,is there any way to get rid of it?
Thanks in advance for any input and advise.







*** Moved by Staff to a more appropriate forum. ***

It is Post Card of Kingdom of SERBIA, actually, issued in 1903, Jun 25.
Michel catalog have this set under number 62-71, set of 10 values, overprinted.
Scott is under number 68-75.
Regarding stains as You call it (or rust around), hardly that it is possible to "clean" it. Many samples of this period have same problem, and it is question of paper and glue, which will go damaged by time, and other reasons.

It looks like they used some kind of glue to adhere a stamp for additional postage.

Makanudo - It is common problem with "classic" stamp on paper. At the time, glue was made from organic material, and with humidity & time, fungi will do job done!