Add Quantities library by Universität Tübingen to section Other libra…

…ries

README.md

@@ -48,6 +48,7 @@ Other libraries
 - [Boost.Units](http://www.boost.org/doc/libs/1_51_0/libs/units/) - Zero-overhead dimensional analysis and unit/quantity manipulation and conversion in C++.
 - [SI](https://github.com/bernedom/SI) - A header only C++ library that provides type safety and user defined literal. Dominik Berner.
 - [quan](https://github.com/kwikius/quan-trunk) - C++ library for physical quantities and much more. kwikius.
+- [Quantities](http://www.echem.uni-tuebingen.de/index.shtml/Quantities/quantities.html) - C++ objects with dimensionality and units attached in a way similar to the built-in types float or double. Universität Tübingen.
 - [units](https://github.com/mpusz/units) - A Physical Units Library for C++ providing compile-time dimensional analysis and unit/quantity manipulation. Mateusz Pusz.
 - [units](https://github.com/nholthaus/units) - A compile-time, header-only, dimensional analysis and unit conversion library built on C++14 with no dependencies. Nic Holthaus.
 - [units](https://github.com/tonypilz/units) - A lightweight compile-time, header-only, dimensional analysis and unit conversion library built on C++11 with no dependencies. Tony Pilz.