College textbooks series

[Devastatingwildness]

Hello,

I have doubts with the concept of a series. I want to add the 2 volumes of a work about college math. I don't know if I should add each volume separately or if I should combine both books with the same ISBN. The publisher webpage sell the 2 volumes all together (here) with the same ISBN. But I have them and two ISBNs appear in each book. The first one is 978-5-88417-040-8, and the second ISBN is a different one for each volume. This is easy to understand —the first ISBN for the whole work and the second one for the volume. So, how should I add these books? Alltogether with the same ISBN or separatelly in a series of books with different ISBNs?

I searched for textbooks examples but I couldn't find any. Do you know any example?

[Sandra]

I would add them with separate ISBNs as some people may only one of the books & not the set.

[Devastatingwildness]

Thank you Sandra, that's what I think. Do you think I should create a series? I see a lot of similar cases but people does not create series. They simply put in the title "Volume 1", "Volume 2", and so on.