Sticker packs.

Since I'm trying to complete the sticker book I noticed that some cards have the initials TIZ and then a number after it which means trouble in zombopolis but when I look in the shop there are no Trouble in zombopolis packs nor the Front line fighters packs. I'm wondering are these packs making a return any time soon, have they just changed names of these packs, and most importantly can I still get these stickers in other packs.