Nucleosides / Linkers / Termini / Part-Specific MS/MS Fragments / Atomic Weights
Sequence
Nucleosides
Linkers
Termini
Composition
The RNA Modification Database The RNA Institute(http://mods.rna.albany.edu/mods)
Modomics(https://iimcb.genesilico.pl/modomics/)
NIST Physical Measurement Laboratory (http://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=&ascii=html&isotype=some)