Specific Offer.......Since it is offered to a particular group(Advocates).......

But isn't it Invitation to offer. Because if  its offer then the publisher is bound to perform his set of promise if the group opts for the books?

Invitation to offer means just making other person to offer you........

But here, he is directly making an offer to sell the books...So if they accept it, he is bound to perform it........

It is "GENERAL OFFER" isn't??

General Offer is the offer to every one.......

But here it is mentioned that it is offered to Group of Advocates....

So it is Specific Offer.......

Definately it is invitation to offer