The W was in a years ago financing and the Z is from a 2019 financing.
You can go back and search both if you want more detail - just take the expiration date and subtract 3 years and that will put you in the area of the F-1 Offerings. Notice the expirations are a year apart, that's how you can tell.
FYI - They also have issued C & D warrants but don't plan to list them.