At the suggestion of the instrumental pedagogues Egon Saßmannshaus and Rudolf Nykrin, Bertold Hummel wrote several easy pieces for two and three violins.

Presto (1976)
Andante (1976)
Musette (1976 )
Autumn Melody (1976)
Siciliano (1976)
Marcia (1976)
in: Egon Saßmannshaus:
Early beginnings on the violin
A violin school for children from the age of 4
Volume 3: Happy duo playing
Bärenreiter BA 6617

The following pieces are from the work

Kinderleichtes Streichkonzert for 2 and 3 violins

Evening Mood (1998)
3+2=5 (1998)
In the cinema: Dunkle Geschäfte (1998)
also in: Bianka Wüstehube / Rudolf Nykrin:
Playing and learning the violin 3
Schott ED 8563

Pieces for 3 violins

Little Melody for Anja (1998)
Overture (1999)
also in: Bianka Wüstehube / Rudolf Nykrin:
Playing and learning the violin 3
Schott ED 8563

for 2 violins with glockenspiel or third violin:

"I hear a little bird whistling ..." (after an Alemannic folk song) (1998)
also in: Bianka Wüstehube / Rudolf Nykrin:
Playing and learning the violin 2
Schott ED 8562

"Ha amen Ort e Blüemli gseh ..." (after an Alemannic folk song) (1998)

The teaching manual also contains Kleiner Marsch (2001) for violin and piano.

Bianka Wüstehube / Rudolf Nykrin:
Playing and learning the violin - manual for lessons
Schott ED 8564

Bertold Hummel's estate still contains these two duos and a song arrangement for 3 voices from the early 1960s:

Little March

Children's Song

My little child, go to sleep