Where can I find websites which detail the rapid economic growth in
Russia during the 18th century and give the reasons for this

Danny,

The economic history of Russian in the 1700's is inextricably linked
to the turbulent political and social reforms and upheavals that took
place throughout much of the 18th century.

You'll find an excellent overview of both the economic growth,
geographic expansion, and great social changes that took place in
Russia at the following sites:



http://lcweb2.loc.gov/frd/cs/rutoc.html
A Country Study: Russia
Library of Congress 


In particular, see the sections:

Early Imperial Russia 

Peter the Great and the Russian Empire 

The Era of Palace Revolutions 

Imperial Expansion and Maturation: Catherine II 


This is a fantastic resource, and you may find this one document has
just about all the information you'll need to get started on your
research.


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For a more condensed version of the same period, see the section on
"Imperial Russia" in the Russian History article from Wikipedia:


http://en.wikipedia.org/wiki/History_of_Russia


===============


You can access a very detailed article on expanision and growth from
the Encyclopedia Britannica:


http://www.britannica.com/eb/article-38530


but it's necessary to sign up for a free trial at the site in order to
read the full article....I recommend it.


===============


Some observations about Peter the Great's influence on the times can
be seen in these excerpts from 18th century observers:


http://www.fordham.edu/halsall/mod/petergreat.html
Modern History Sourcebook: 
Peter the Great and the Rise of Russia, 1682-1725


===============


There's a pretty good 'quickie' version of Russian history and
economic growth here:


http://www.geographia.com/russia/rushis04.htm


===============


If you really want to dive in deep, check out this online history book from 1859:


http://www.hti.umich.edu/cgi/t/text/pageviewer-idx?c=genpub&cc=genpub&xc=1&idno=aba3661.0001.001&xg=1&q1=russia&frm=frameset&view=image&seq=16


John Stevens Cabot, 1805-1877. 
The empire of Russia; from the remotest periods to the present time. 


The chapters on Peter the Great begin with Chapter 20 -- you'll have
to pull up the book page images one page at a time.

This is a terrific historical source, but the economics (about the
growth of St Petersburg, building of manfuacturing industries, etc)
are strewn throughout, so you'll have to do a bit of digging.


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I trust these information sources fully meet your needs.  

However, please don't rate this answer if you find you'd like
additional information.  Just post a Request for Clarification to let
me know how I can assist you further, and I'm at your service.

All the best,

pafalafa-ga


search strategy -- visited bookmarked sites for history and accessed
information on Russia in the 18th century.

Researcher was very helpful, providing extremely accurate information
as well as additional information which was not requested but
extremely useful.  Highly recommended.