The D minor/major seventh chord is a 4-note chord consisting of the notes D, F, A and C#.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Dm/ma7.
Chords that are a superset of Dm/ma7. The chords include more notes but always D, F, A and C#.
Chords that are a subset of Dm/ma7. These contain less notes but all of them are included in Dm/ma7.
In case you prefer a non-interactive variant of the chord chart, we've embedded a PNG image below that shows the notes for the the Dm/ma7 chord. Feel free to save or share the image as needed.