Properties not listed on MLS

[Takeshi Yashima]

Hi,

I drove around the target neighborhood to find my 1st income property. I saw a lot of properties with listing agent information. So I wrote down the information on each property and then, I went back to home to check how much are those properties cost assuming that those properties are on the MLS (since listing agent name and contract information was there). However, none of those properties information listed on MLS. But according to the public information, some of them were sold long time ago (6 months to a year ago). Does this mean that those properties have not been listed in MLS yet? If so, am I supposed to contact directly to listing agent? Or is there any good way to approach these kind of properties?

Any help will be appreciated.