It was observed for the first time on January 30, 2011.

It was observed for the first time on January 20, 1986.

In 2009, Singapore observed the day for the first time.

In 2010, this species was observed for the first time since its 1941 description.

It was observed experimentally for the first time in 1958.

The holiday was observed for the first time on October 1, 1991.

Day is officially observed for the first time in all 50 states.

When the revolution of 1959 occurred, divorce rates were starting to be observed for the first time.

In 2010, this species was observed for the first time since 1967.

In 2010, geo-neutrinos from Earth's interior have been observed for the first time.