Together with his friend Holger, Dieter formed the duo Monza. They recorded two songs : Hallo Taxi nr. 10 and Heiße Nacht in der City. I could be wrong, but these singles are the very first ones, on which Germany saw Dieter Bohlen for the first time !!!
When you will take a look to the singles you will notice on the first one, the names T. Hendrik and K. van Haaren. I'm sure that a lot of you will recognize these names as the brain behind the group Bad Boys Blue, also from Germany ...
For some reason, I like the B sides more...

 

Hallo Taxi Nummer 10
3'48"

Cola und rock 'n' roll
4'08"

1978

This is the very first single with Dieter's voice on it !!!

A side
Written by T. Hendrik / K. van Haaren / F. Thorsten
Arranged by Ralf Nowy
Produced by T. Hendrik und K. Hartmann
B side
Written by David Bellamy / K. van Haaren
Arranged by Ralf Nowy
Produced by T. Hendrik und K. Hartmann

Heisse Nacht in der City
3'07"

heissenacht.jpg - 55668 Bytes
Ginny
3'28"

1978
A side
Written by Nick Gilder / James McCulloch - Dieter Bohlen
Arranged and conducted by Ralf Nowy
Produced by Mario Aita
B side
Written by Dieter Bohlen / Dieter Bohlen
Arranged and conducted by Ralf Nowy
Produced by Mario Aita

There's a small German text on the backside of this single. In English, it's something like this :

Monza are Dieter Bohlen (24 years old) and Holger Garboden (20 years old). About 6 months ago, we heard them for the first time with the single Hallo Taxi Nr. 10. The new single Heisse Nacht in der City is the German version of the US-tophit Hot Child in the city by Nick Gilder.

As you see, both singles were released in 1978. So this means that the first Dieter Bohlen single was released between January and July of the year 1978 !