How do I determine the pronounication of compound nouns such as 来年夏.
Obviously 来年の夏 is pronounced らいねんのなつ but what happens when I remove the の? Does it just become らいねんなつ? My guess from everything I've read is that it's more likely to use an 音読み reading, which gives me a choice of らいねんか or らいねんげ. It would be quite vexing if simply omitting the の changes the pronunciation, but I fear this may be the case.
Compounds like this don't appear in any dictionaries I've seen, so are there some general rules to apply?
Here's another example from the same article: 登山者数. Is it とざんしゃかず or とざんしゃすう