L-Tryptophan-L-Glutamine-L-Cysteine-Selenium.jpg

symbols for L-Tryptophan, L-Glutamine, L-Cysteine, Selenium

All images from Wikimedia Commons. L-Tryptophan, L-Glutamine, L-Cysteine are public domain. Selenium is CC BY-SA 2.0 UK by Greg Robson.