Disc recording of N. N. Poppe on the Academy of Sciences parts 1 and 2
Conditions Governing Access note
Disc recording of N. N. Poppe on the Academy of Sciences part 9
Disc recording of N. N. Poppe on the Academy of Sciences part 12
Disc recording of N. N. Poppe on the Academy of Sciences part 15
Disc recording of N. N. Poppe on the Academy of Sciences parts 19 and 20
Disc recording of N. N. Poppe on the Academy of Sciences parts 21 and 22