Update README.md

README.md

@@ -12,6 +12,9 @@ Please have a look at our [OpenSense wiki](https://gitlab.ethz.ch/tec/public/ope
 ### Ultrafine Particle Dataset
 Two and a half years (04/2012-12/2014, >36 Mio samples) of UFP data collected by the mobile sensor network can be found here: [https://zenodo.org/record/3298842](https://zenodo.org/record/3298842)
 
+### Ozone and Carbon Monoxide Dataset
+Over four years of ozone (O3) and two years of carbon monoxide (CO) measurements (~70 Mio. samples) by the mobile sensor network can be found here: [https://doi.org/10.5281/zenodo.3355208](https://doi.org/10.5281/zenodo.3355208)
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 ### Test datasets
 Two test datasets can be found here:
 * [Ozone (O3)](data/ozon_tram1_14102011_14012012.csv)