Find multiple matches starting with specific symbols and then consecutive occurrences of specific words and patterns

Question

I have the following kind of string "sometext1 §§ 12 Abs. 5, 13a, 14 Satz 1 Nr. 3, 9, 8 sometext2". I want to find a §§ substring and all consecutive occurrences of Abs., und, Satz and Nr. as well as digits with a single character like 13a.

Examples:

"Die Anzahl der §§ 12 Abs. 5, 13a, 14 Satz 1 und 8 kann variieren. Für die §§ 15a, 18 Abs. 5, 21 und 23 Satz 3 trifft dies nicht zu.

Here I want to get 12 Abs. 5, 13a, 14 Satz 1 und 8 and 15a, 18 Abs. 5, 21 und 23 Satz 3.

I used the following regex 'r'§§ (.*)? ^(?!Satz|Abs.|Nr.|\d+[a-z]| |,)'.