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Waterfalls form where a river flows over a steep precipice in its course.
Structures consisting of enormous stone blocks, dating back thousands of years, are monuments of megalithic cultures.
Butyric acid (or butanoic acid) is a saturated monocarboxylic acid.
Terephthalic acid is an aromatic dicarboxylic acid.
In the disciplines dealing with the human body, it is extremely important to precisely specify the planes, axes and directions.
The Hussites mastered the use of war wagons in the 15th century.
A regular square pyramid is a right pyramid with a square base and four triangular faces.
An important archaeological site located on the right bank of the Danube in eastern Serbia, within the Iron Gates gorge.
Bulgaria's natural resources include a great variety of minerals.
This scene presents the climate zones and soil types of Bulgaria.
This scene presents the provinces and provincial capitals of the Netherlands.
Today called Dubrovnik, this Croatian city is known for its spectacular architecture and beautiful location.
Many of the most important food crops we consume belong to the family of nightshades.
The raw material of chocolate, cocoa powder and cocoa butter is provided by a tropical plant.
An invasive predatory sea snail species that inhabits warm seas.
Organs that detect signals of the environment or of the body and transmit them to the brain as nerve impulses.
A canid similar to the wolf but smaller in size and more delicate in appearance.
Riverbed engineering refers to artificial modification of the course or flow of rivers.
This animation helps you learn the basics of healthy eating.
The migration of large human populations began in Ancient times.
The animation shows the city of Szeged before it was devastated by the great flood.
Remarkable civil engineering works to continue the Netherland's centuries-long fight against the sea.
There are various types of instruments used for measuring temperature.