the key is corenodeid in NCM_NodeProperties table then use NCMs nodeid=ncms nodeid...
select n.Caption, ncmep.serial
from Nodes n
inner join NCM_NodeProperties ncm on n.NodeID=ncm.CoreNodeID
inner join NCM_Entity_Physical ncmep on ncm.NodeID=ncmep.NodeID
where n.Caption like '%<routername>%'
or you can filter differently with the where clause... I got a bunch of results for the one device (27 rows) for modules, etc...