na Jan Steffen, Rukunin Ƙarfafa Tushen - Zamantakewa, Muhalli, da Haɗin Al'adu a cikin Al'ummomin da suka gabata

Yayin da duniya ke fuskantar kalubale na sauyin yanayi a halin yanzu, binciken kimiyya na daga cikin manufofinsa, nazarin yadda al'ummomin bil'adama...