Sommer, B., & Pötzsch, O. (2003). Population of Germany Today and Tomorrow. Metzler-Poeschel.
Lua i Stíl Chicago (17ú heag.)Sommer, Bettina, agus Olga Pötzsch. Population of Germany Today and Tomorrow. Wiesbaden: Metzler-Poeschel, 2003.
Lua MLA (8ú heag.)Sommer, Bettina, agus Olga Pötzsch. Population of Germany Today and Tomorrow. Metzler-Poeschel, 2003.
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