they are of the 3.5'' form factor if that can help
However I dont know what kind of controller to buy and what cable that I should use to connect them. I've searched a lot on google but I havent found anything yet. Do you know how I can identify the correct connector types and the correct SAS controller card I should buy?
Most SAS controllers today use a SFF-8087 type connector normally called mini-sas. This can then plug directly into backplanes, SATA hard drives, SAS hard drives and other connections. For you to use a SAS hard drive without a backplane you will need this cable. (or one like it)
There are a few different SAS cards listed there. But you can use any SAS controller you want either RAID or not. I would stick to Adaptec, 3ware, or Intel/LSI. If you get a really old controller in may have a different interface and you would need that cable type accordingly, which is most likely also listed on that page above.
I cant tell from that picture you linked to if the adapter is attached or if it come off allowing a SATA tyoe power connection. I have seen some older Adaptec cables that were attached and you could not remove them. The cable I linked to provides a SATA connection for power and also comes with the adapters. I use this cable for my SAS drives and connect it directly to a SATA power connection.