On 'Comparison of the chemical properties of selenocysteine and selenocystine with their sulfur analogs' by R.E. Huber and R.S. Criddle.

Selenium was initially considered a toxic element found in plants growing in soils rich in this element. However, a few years later, selenocysteine was recognized as the 21st amino acid. Huber and Criddle's article has been crucial in discovering selenium-containing proteins and other related works on selenocysteine.