Hmmm... I'm not sure I understand but it depends what you mean by "special buildings".
If you mean things like the oil refinery or metal and alloy smelter, then yes, those are add ons for the primary specialization buildings. The oil refinery, for example, allows you to turn your extracted oil into things like plastic and fuel. You must supply these buildings with oil, then they will produce the fuel and plastic as you plop the necessary add-ons. Then you must also plop some fuel and/or plastic storage lots. Then you can start selling it on the global market for profit.
As explained before, the amount of profit made from these buildings will go up and down depending on supply of oil. Hope that answered your question.
If you mean things like the oil refinery or metal and alloy smelter, then yes, those are add ons for the primary specialization buildings. The oil refinery, for example, allows you to turn your extracted oil into things like plastic and fuel. You must supply these buildings with oil, then they will produce the fuel and plastic as you plop the necessary add-ons. Then you must also plop some fuel and/or plastic storage lots. Then you can start selling it on the global market for profit.
As explained before, the amount of profit made from these buildings will go up and down depending on supply of oil. Hope that answered your question.