Source: http://www.chtf.stuba.sk/~szolcsanyi/education/files/Organicka%20chemia%20II/Prednaska%208_Aminokyseliny%20a%20peptidy/Doplnkove%20studijne%20materialy/Amide%20bond%20formation/Amino%20acid%20chlorides%20-%20a%20journey%20from%20instability%20and%20racemization.pdf