It depends on the sentence. Example 1: "Go grab those other two books." This means they want you to grab two specific books that we already talked about and have in our thoughts. Example 2: "Go grab two other books." This means to go grab two random books from somewhere, other than the one you have. In the case of your sentence, "...as well as two other books." This is the only way you can say this. "...as well as other two books," is wrong. However, "...as well as those other two books," is correct. The word "those" places emphasis on something you already have in your mind and likely talked about with someone.