1. Brown DJ (1988) Fused pyrimidines, pt 3. pteridines. Wiley, New York
2. Hurst DT (1980) Chemistry and biochemistry of pyrimidines, purines and pteridines. Wiley, New York, p 64
3. Pfleiderer W (1992), J Heterocycl Chem 29: 583
4. The name pyrimido[4,5-b]pyrazine was adopted by Chemical Abstracts for a period of time and sometimes appears in older literature
5. Albert A (1976) Adv Heterocycl Chem 20: 117