Hi,
If it helps, the full query reference is here: http://codex.wordpress.org/Class_Reference/WP_Query
I think you can just use post_type, separating the types with commas. For example, for posts & units:
query="post_type=post,units"
You can also use this to get all post types (in which case you’ll need to identify the relevant posts by category, tag, or something else):
query="post_type=any"