http://www.geocities.com/SiliconValley/2527/presentperfect.html

http://www.englishpage.com/verbpage/presentperfect.html

http://www.eclecticenglish.com/grammar/PresentPerfect1A.html

http://www.englishclub.com/grammar/verb-tenses_present-perfect_u.htm

http://www.english-at-home.com/grammar/how-to-use-...ent-perfect-tenses-in-english/

http://www.langust.ru/unit_in/unit007i.shtml

http://www.englisch-hilfen.de/en/grammar/present_perfect_use.htm

http://leo.stcloudstate.edu/grammar/tenses.html

http://cad.ntu-kpi.kiev.ua/~demch/friends/esl4rus/presentperf.html

http://grammar.about.com/od/pq/g/prespertense.htm

http://www.eslcafe.com/grammar/present_perfect_progressive_tense05.html

http://www.voanews.com/specialenglish/archive/2004-08/a-2004-08-11-3-1.cfm

http://www.grammar-quizzes.com/presperfsum.html

http://www.ling.canterbury.ac.nz/documents/RCoxthesis.pdf


просто можно ввести в google.com в строку поиска: usage present perfect filetype:pdf
еще можно ввести meaning present perfect filetype:pdf