Some great online resources that I can recommend without reservation.

http://thepatternsite.com/at.html

http://stockcharts.com/school/doku.php?id=chart_school:chart_analysis:chart_patterns:ascending_triangle_continuation

http://www.investopedia.com/university/charts/charts5.asp

But I would caution against calling a pattern until there are at least 4 alternating price contacts with the pattern boundaries - 2 for each line - and then also always remember that what looks like one thing often "morphs" into something else. With 4000 being such an important figure, it could be a straightforward A-B-C developing.