Good business studies books include Longman and Jacaranda.
The excel book is quite brief, but it's ok if you just want to get a general overview over the topcis. Leading edge is also alright, but it is usually the best for economics.
Yeap, i've got the biology in contexts book, pretty detailed though, I heard that it's the best bio book out there. And for my other subjects I've got a whole lot of other supplement textbooks + study guides.