What were gorbechev's reform effort called ?

Why is it useful for historians to base certain studies on the analysis of historical themes

"if i have seen farther than others," said newton, "it is because i have stood on the shoulders of giants." who were the giants to whom newton was referring? could this be said of any scientific accomplishment? explain.

Describe the geography of the nile valley . how did this geography affect civilizations that emerged in the nile valley