C++でtwitter apiを試してみようとしターミナル(OSX)でmakeをすると以下のようなエラーが出ます解決策が分かる方教えてください

g++ -o tweet hash.o oauth.o sha1.o webclient.o tweet.o main.o -lssl
Undefined symbols for architecture x86_64:
"_ERR_error_string_n", referenced from:
WebClient::https_get(URI const&, WebClient::Post const*, std::__1::vector<char, std::_1::allocator<char> >*) in webclient.o
ssend(ssl_st*, char const*, int) in webclient.o
"_ERR_free_strings", referenced from:
WebClient::https_get(URI const&, WebClient::Post const*, std::__1::vector<char, std::__1::allocator<char> >) in webclient.o
"_ERR_get_error", referenced from:
WebClient::https_get(URI const&, WebClient::Post const, std::__1::vector<char, std::_1::allocator<char> >*) in webclient.o
ssend(ssl_st*, char const*, int) in webclient.o
"_RAND_poll", referenced from:
WebClient::https_get(URI const&, WebClient::Post const*, std::__1::vector<char, std::__1::allocator<char> >) in webclient.o
"_RAND_seed", referenced from:
WebClient::https_get(URI const&, WebClient::Post const, std::__1::vector<char, std::__1::allocator<char> >) in webclient.o
"_RAND_status", referenced from:
WebClient::https_get(URI const&, WebClient::Post const, std::__1::vector<char, std::__1::allocator<char> >) in webclient.o
"_iconv", referenced from:
conv(char const, char const*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) in tweet.o
"_iconv_close", referenced from:
conv(char const*, char const*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) in tweet.o
"_iconv_open", referenced from:
conv(char const*, char const*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) in tweet.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [tweet] Error 1