If you choose in the left-hand column (the menu) Topics, you will reach the page with four themes: Persons, Organisations, Places and Events. Each of the themes is divided into a number of topics. The name of a topic links with a page that gives a description. Below the description there are links to all the stamps, that are devoted to this topic. There is also a link to an external information source, most of the time the internet encyclopaedia Wikipedia.

If you choose in the menu Countries a table is shown with alle countries of wich Polonica stamps are known. By clicking on a country you reach a page with descriptions of all the stamps and pictures, if available.
All words that contain a link are yellow, like the example below.

Links
A good internet catalogue of the stamps, engraved by Czesław Slania you find on: http://www.slaniastamps-heindorffhus.com
A more than complete catalogue of Poland and related territories is: Stamp Encyclopaedia Poland