Question on clothing quality

I am about to buy a few new dress shirts, and I have done a little
research on what to look for in terms of quality. Multiple sources
say to look for "single–needle stitching," which means that the shirt
is only sewn with one needle on one side at a time. My problem is,
I'm having a hard time visualizing what a seam like this would look
like in person, when I'm actually looking for shirts. Would there be
any online resources/images that would help me out, or could someone
give me a more detailed description as to what this seam would look
like?
Thanks so much,
Josh