Generally, a string quartet consists of two violins, a viola, and a cello. However, a quartet can be made up of all sorts of variations on this model.
Two violins,viola and violoncello
1st violin 2nd violin Viola Cello
Two violins, a viola and a cello is the standard.
You can get used string instruments from countless local music shops. If you use google maps you can find a very long list of the shops nearest you.
a violin, viola and a cello or two violins and a cello
You would find violins, cellos and maybe a Double Bass.
Traditionally, we can find a violin, cello, viola, and bass used in an orchestral arrangement.
I would look for a store, maybe in a big city, that specializes in banjos and acoustic string instruments, and give them a call.
Look in the volume with U in it. It may cross reference to an entry on musical instruments or string instruments. Most encyclopedias will have an index that can give you the actual page for the entry.
Number, string, binary string.
Asteria are a quartet who play string instruments. Although their official website says they trained together it is not possible to find out their names from there or elsewhere.
Strings, woodwinds and percussion instruments were used in the romantic period orchestra. Small scale instruments were used during this period.