Proprietary rights and acknowledgements:

NMDB distributes official data provided by the PIs of the neutron monitor stations. Data of different origin may not have been validated or authorised by the respective PI, and any deviation with respect to the authorised data is not his/her responsibility.

Data retrieved via NMDB are the property of the individual data providers. These data are free for non commercial use within the restrictions imposed by the providers. If you use such data for your research or applications, please acknowledge the origin by a sentence like "We acknowledge the NMDB database (www.nmdb.eu), founded under the European Union's FP7 programme (contract no. 213007) for providing data, and the PIs of individual neutron monitors at: Nor-Amberd (Cosmic Ray Division, CRD, of A.I. Alikhanyan National Science Laboratory, Yerevan, Armenia)"

Acknowledgement of other data sources where relevant

Smoothed Sunspot Numbers and Monthly Sunspot Numbers are provided by the Solar Influences Data Analysis Center (SIDC), Royal Observatory of Belgium.

Kp 3-hourly index is provided by the Deutsches GeoForschungsZentrum Postdam (GFZ) in cooperation with the International Association of Geomagnetism and Aeronomy (IAGA) and the International Service of Geomagnetic Indices (ISGI). DOI of the Kp dataset

GOES proton flux data is provided by the United States NOAA/National Geophysical Data Center (NGDC)

"original" and "revised" data in NMDB:

Neutron monitor count rates are available through NMDB in various versions. Data called "original" are the count rates of a given monitor as provided by this monitor's registration system. Depending on the neutron monitor station these data may have been modified by real-time quality checking procedures, which correct obvious short-lived instrumental effects such as spikes or data gaps produced by hardware and software disturbances, as well as erroneous atmospheric pressure measurements. These corrections are made under the responsibility of the data provider who also archives the raw data. "Revised" data contain further corrections made during subsequent analyses.
More information on the NMDB format can be found here.