I would really appreciate any help in regards to textbooks you could give that I may study undergraduate maths from. I have recently become fascinated by maths through recent exposure to Euclid's "Elements". I was already self-studying the maths A level and am just about finishing studying and learning everything contained in the revision book I learnt A level mathematics from. As I am in Year 12 I have over a year and a half to go before I can go to university and do not see any reason behind waiting that long to start studying undergraduate level work. What textbooks or other sources would you recommend so that I may increase my knowledge of mathematics? I am particularly interested in anything in any other fields like Euclid's "Elements" where everything is proven from a small foundation of axioms and such; that is if there are such comprehensive books in other areas. I do not really mind how complex they become as long as they begin with the knowledge that the average undergraduate would be in possession of and do not progress without explaining any new notation I would be unfamiliar with. Thank you very much in advance to anyone who is able to help me.