In 1869, Mendeleev's first periodic table did not include them, as closed-shell elements remained undiscovered ... after observing 'drunkenness' in deep-sea divers, and it was first used for ...

Bulgaria has signed a five-year agreement with Shell to explore for oil and gas in Block 1-26 Khan Tervel, located within the country’s exclusive economic zone in the Black Sea. The move marks a ...

Shell (NYSE:SHEL) has signed a contract with Bulgaria's government for the rights to explore for oil and gas in the Black Sea, the country's energy minister said Tuesday. The contract will allow ...