[C++] Windows e curl

[fermat]

ciao!
ho installato cygwin su windows 7 e tra i pacchetti ho installato anche curl.
ho creato questa funzione:

void Read::readUltimeEntrate() {
    curl_slist_append(headers, "Accept: application/json");
    curl_slist_append(headers, "Content-Type: application/json");
    curl_slist_append(headers, "charsets: utf-8");
    curl = curl_easy_init();
    if (curl) {
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
        curl_easy_setopt(curl, CURLOPT_URL, "http://example.com/file.php");
        curl_easy_setopt(curl, CURLOPT_HTTPGET, 1);
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
        res = curl_easy_perform(curl);
        if (CURLE_OK == res) {
            char *ct;
            res = curl_easy_getinfo(curl, CURLINFO_CONTENT_TYPE, &ct);
            if ((CURLE_OK == res) && ct) {
                res = curl_easy_perform(curl);
                cout << res << endl;
            }
        }
    }
    curl_easy_cleanup(curl);
}

nel file h ho incluso la libreria <curl/curl.h>.
quando vado ad eseguire il programma mi escono tutti questi errori:

build/Debug/Cygwin-Windows/read.o: In function `_ZN4Read17readUltimeEntrateEv':
/cygdrive/c/Users/admferrone/Desktop/Banca/read.cpp:14: undefined reference to `_curl_slist_append'
/cygdrive/c/Users/admferrone/Desktop/Banca/read.cpp:15: undefined reference to `_curl_slist_append'
/cygdrive/c/Users/admferrone/Desktop/Banca/read.cpp:16: undefined reference to `_curl_slist_append'
/cygdrive/c/Users/admferrone/Desktop/Banca/read.cpp:17: undefined reference to `_curl_easy_init'
/cygdrive/c/Users/admferrone/Desktop/Banca/read.cpp:19: undefined reference to `_curl_easy_setopt'
/cygdrive/c/Users/admferrone/Desktop/Banca/read.cpp:20: undefined reference to `_curl_easy_setopt'
/cygdrive/c/Users/admferrone/Desktop/Banca/read.cpp:21: undefined reference to `_curl_easy_setopt'
/cygdrive/c/Users/admferrone/Desktop/Banca/read.cpp:22: undefined reference to `_curl_easy_setopt'
/cygdrive/c/Users/admferrone/Desktop/Banca/read.cpp:24: undefined reference to `_curl_easy_perform'
/cygdrive/c/Users/admferrone/Desktop/Banca/read.cpp:28: undefined reference to `_curl_easy_getinfo'
/cygdrive/c/Users/admferrone/Desktop/Banca/read.cpp:30: undefined reference to `_curl_easy_perform'
/cygdrive/c/Users/admferrone/Desktop/Banca/read.cpp:35: undefined reference to `_curl_easy_cleanup'
collect2: ld returned 1 exit status
make[2]: *** [dist/Debug/Cygwin-Windows/banca.exe] Error 1
make[1]: *** [.build-conf] Error 2
make: *** [.build-impl] Error 2

da cosa può dipendere??