The relevant sentence in the passage is: The terminology was made popular by Henri Tajfel and colleagues during his work in formulating social identity theory.
Henri Tajfel and colleagues
The terminology was made popular by Henri Tajfel and colleagues during his work in formulating social identity theory. The significance of ingroup and outgroup categorization was identified using a method called the minimal group paradigm. Tajfel and colleagues found that people can form self-preferencing ingroups within a matter of minutes and that such groups can form even on the basis of seemingly trivial characteristics, such as preferences for certain paintings.

Who introduced the term in group and out group?

This is the relevant information: They remained there for six months, from December 19, 1777 to June 19, 1778.
from December 19 , 1777 to June 19 , 1778
Passage: Valley Forge functioned as the third of eight military encampments for the Continental Army's main body, commanded by General George Washington. In September 1777, British forces had captured the American capital of Philadelphia. After failing to retake the city, Washington led his 12,000-person army into winter quarters at Valley Forge, located approximately 18 miles (29 km) northwest of Philadelphia. They remained there for six months, from December 19, 1777 to June 19, 1778. At Valley Forge, the Continentals struggled to manage a disastrous supply crisis while retraining and reorganizing their units. About 1,700 to 2,000 soldiers died due to disease, possibly exacerbated by malnutrition.

Question: Based on this passage, when did the winter at valley forge happen?

To answer this question, we should know that: Vega, Lyra's brightest star, is one of the brightest stars in the night sky, and forms a corner of the famed Summer Triangle asterism.
Vega

Vega, Lyra's brightest star, is one of the brightest stars in the night sky, and forms a corner of the famed Summer Triangle asterism. Beta Lyrae is the prototype of a class of stars known as Beta Lyrae variables. These binary stars are so close to each other that they become egg-shaped and material flows from one to the other. Epsilon Lyrae, known informally as the Double Double, is a complex multiple star system. Lyra also hosts the Ring Nebula, the second-discovered and best-known planetary nebula.

Brightest star in the constellation lyra dan word?