Undefined Refrence

/tmp/ccCiqUTT.o: In function `Assimp::Importer::ReadFile(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, unsigned int)':
Mesh.cpp:(.text._ZN6Assimp8Importer8ReadFileERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEj[_ZN6Assimp8Importer8ReadFileERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEj]+0x30): undefined reference to `Assimp::Importer::ReadFile(char const*, unsigned int)'
/tmp/ccCiqUTT.o: In function `aiMaterial::GetTexture(aiTextureType, unsigned int, aiString*, aiTextureMapping*, unsigned int*, float*, aiTextureOp*, aiTextureMapMode*) const':
Mesh.cpp:(.text._ZNK10aiMaterial10GetTextureE13aiTextureTypejP8aiStringP16aiTextureMappingPjPfP11aiTextureOpP16aiTextureMapMode[_ZNK10aiMaterial10GetTextureE13aiTextureTypejP8aiStringP16aiTextureMappingPjPfP11aiTextureOpP16aiTextureMapMode]+0x49): undefined reference to `aiGetMaterialTexture'
/tmp/ccCiqUTT.o: In function `aiMaterial::GetTextureCount(aiTextureType) const':
Mesh.cpp:(.text._ZNK10aiMaterial15GetTextureCountE13aiTextureType[_ZNK10aiMaterial15GetTextureCountE13aiTextureType]+0x1c): undefined reference to `aiGetMaterialTextureCount'
/tmp/ccCiqUTT.o: In function `Model::loadModel(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)':
Mesh.cpp:(.text._ZN5Model9loadModelERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE[_ZN5Model9loadModelERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE]+0x28): undefined reference to `Assimp::Importer::Importer()'
Mesh.cpp:(.text._ZN5Model9loadModelERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE[_ZN5Model9loadModelERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE]+0x71): undefined reference to `Assimp::Importer::GetErrorString() const'
Mesh.cpp:(.text._ZN5Model9loadModelERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE[_ZN5Model9loadModelERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE]+0x124): undefined reference to `Assimp::Importer::~Importer()'
Mesh.cpp:(.text._ZN5Model9loadModelERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE[_ZN5Model9loadModelERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE]+0x159): undefined reference to `Assimp::Importer::~Importer()'
collect2: error: ld returned 1 exit status