Wertschätzung von Belegen: Zeppelinpost / Ad Astra Afrikaflug

Wir haben folgende Anfrage an die Redaktion erhalten. Wer kann helfen ? Vielen Dank im Voraus.

Dear Sir,

First excuse my bad english but I am French. I hope you will understand my message.
I found your email address on internet as Germany stamps specialist and may be you could help me.
I collect French and French colonies stamps, and I just bought an important accumulation of covers.

In it I found some foreign items, especially 2 strange covers : 1 from 1929 with a German stamp but also with Italian ones
and 1 from 1930 with German stamps but with also stamps from Switzerland.

I join pictures.

Could you please tell me more about those covers, especially their value ?

Thank you very much in advance and best regards from France.