I studied these volumes (all four of them, including the one on knives) in their original language, Spanish, when they first come out.
I - personally - don't think the first volume needs the other 2 (3, if you count the knives' one) to be appreciated. The other two volumes contain tricks published by Ascanio in various books and magazines, lecture notes, tapes, etc. and while they show his theories applied to effects, do not always stress on the theoretical principle, being most devoted to the practical side of the effect, its technique. The theory is, of course, behind and in some tricks ("Los Dias Negros" - The Black Days) is discussed again, but most tricks are just a sequence of technical handling details.
The book on knives is a world on its own, as it is a reprint of the scarce volume first published in the fifties and difficult to obtain. It is more a collection of moves and techniques than a theoretical study of the art of magic.
I would recommend to start studying the first volume while waiting for the other two... I sometimes re-read it and always find something new.
Just my 2 cents, ciao!
Marco Pusterla - http://www.mpmagic.co.uk/