From the amidophenylpropiolic acid to kynuren acid and their relatives.

[21] SKRAUP, MONATSH CHEM, V7, P518

[22] SKRAUP, MONATSH CHEM, V10, P726

[23] SKRAUP, MONATSH CHEM, V9, P821

[24] SKRAUP, MONATSH CHEM, V8, P801

[25] VONBAEYER, 1882, BER DTSCH CHEM GES, V15, P2151

[26] VONBAEYER, 1882, BER DTSCH CHEM GES, V15, P2147

[27] VONBAEYER, 1882, BER DTSCH CHEM GES, V15, P2153

[28] VONLIEBIG, ANN CHEM, V86, P125

[29] VONLIEBIG, ANN CHEM, V108, P354

[30] VONNIEMENTOWSKI, 1894, BER DTSCH CHEM GES, V27, P1396

[21] SKRAUP, MONATSH CHEM, V7, P518

[22] SKRAUP, MONATSH CHEM, V10, P726

[23] SKRAUP, MONATSH CHEM, V9, P821

[24] SKRAUP, MONATSH CHEM, V8, P801

[25] VONBAEYER, 1882, BER DTSCH CHEM GES, V15, P2151

[26] VONBAEYER, 1882, BER DTSCH CHEM GES, V15, P2147

[27] VONBAEYER, 1882, BER DTSCH CHEM GES, V15, P2153

[28] VONLIEBIG, ANN CHEM, V86, P125

[29] VONLIEBIG, ANN CHEM, V108, P354

[30] VONNIEMENTOWSKI, 1894, BER DTSCH CHEM GES, V27, P1396