How to query multiple Browse Nodes with Amazon Product Advertising API?

http://ift.tt/1f5d9Nk?
Service=AWSECommerceService&
AWSAccessKeyId=[AWS Access Key ID]&
Operation=ItemSearch&
BrowseNode=123456&
SearchIndex=Books
&Timestamp=[YYYY-MM-DDThh:mm:ssZ]
&Signature=[Request Signature]

How to search multiple BrowseNodes, such as 123456 and 222222?