I'm writing up a report on an experiment I did involving liquid nitrogen. I need to state the boiling point of liquid nitrogen (77.36K) in the report, as I've used it in calculations, but I don't know if I should get a reference for it or not. I did use a reference (Wikipedia and Google searches) to find the 77.36K value, but I don't know whether it is common to assume that a physical property of a substance like its boiling temperature is correct in scientific reports without citing a source. And, if I do need to reference a source for the boiling point, does anyone know of a good source to use? Would I find this value in a journal somewhere? Also, is there an error on 77.36K? An error on this temperature would be helpful to propagate through to my final results' errors. Finally, I'd like to know how the value of 77.36K was established. Was it one study that conclusively found this value to be 77.36K, a general consensus amongst professionals, or is it defined as that value (in the way that 100 degrees Celsius is defined as the temperature of the boiling point of water at sea level)? Help would be appreciated.