>> Amazon has no obvious way to search for a book in a series.
Try typing something like "Jack Reacher series" into the search box and look at the search suggestions as you are typing. Amazon's actually pretty good at helping you find this sort of thing - which makes sense, given the likely propensity of consumers to purchase all the items in a series if they're available and Amazon's financial incentive to help the consumer do so.
Third-party listings, on the other hand, are more of a challenge. Limiting your search to Prime-eligible items often helps quite a bit.
Try typing something like "Jack Reacher series" into the search box and look at the search suggestions as you are typing. Amazon's actually pretty good at helping you find this sort of thing - which makes sense, given the likely propensity of consumers to purchase all the items in a series if they're available and Amazon's financial incentive to help the consumer do so.
Third-party listings, on the other hand, are more of a challenge. Limiting your search to Prime-eligible items often helps quite a bit.