R. Kolář: Manual for searching in the six-lingual web catalogue....

1. Manual for searching in the six-lingual web catalogue
Probably the most detailed structured thematic philatelic web catalogue worldwide so far / still free in six European languages.
There is also given catalogue number of Michel and Yvert which are most commonly used in Europe (for some also Scott number). It is possible to search e.g. at the following links and update specific country, region or year of issue but also by a keyword e.g. personality or select from more than hundreds of topics.
- for us focusing on Archeology, Arctica + Antarctica, Atom, Energy, Folklore, Chemistry, Geology, mining, Nobel, etc.
BECAUSE OF MANY QUESTIONS TO METHOD OF DISPLAYING, I present the Instructions for use:
after activation
http://www.freestampcatalogue.com/app
this link can not be opened directly from the previous line but must be copied
http://www.postbeeld.com/en/fsc/home/app
In the top black bar on the far right, adjust the displaying language. Then, in the white virtual table select the icon (COUNTRY), the specific region and you can view all the commonly issued stamps, se-tenants and miniature block-sheets. 
Then select icon (TOPIC), where plenty of topics are listed, or icon (YEAR) – year of issue.
Under the displayed stamps the year of issue is stated, together with catalogue number, price in euro and possibility to order by the shopping cart icon.
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2. Universal Postal Union (UPU) also enable searching of e.g. occasional commemorative postmarks, Card maximum, stamps, surcharges, FDC etc.
(instructions for opening)
- using web offers of individual regional postal companies (independent system)
(návod k otevření) 
 –  pomocí www nabídek jednotlivých územních poštovních společností (nezávislý systém) www.upu.int
This is the main page from where it is possible to search throught up to national name of postal organization
activate:
on the top bar – The UPU
in the left column – Member countries
after activation, the list of member countries in alphabetical order will appear
http://www.upu.int/en/the-upu/member-countries.html
it is also possible to open an individual country, mentioning the name of the national postal organization and country abbreviation according to ISO Code 3166/Alpha-2 („cz“ for the Czech Republic). 
after activation of the national title of the postal organization, you will open official website, where is possible to search issued postage stamps, FDC, envelopes with surcharges, commemorative postmarks, etc.
for example:
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Slovak Post Office – Catalogue – Products – Postmarks etc.
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Czech Post – Philately - commemorative postmarks, etc.
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Chile – Products – Fila, etc.
I recommend to first test on the Czech and Slovak post office and then try the foreign ones.
Radoslav Kolář