Here is the official answer

Just search the 1040 instructions, here is the instruction on dual status:

if you were a U.S resident on the last day of the tax year, file form 1040. Enter "Dual_status REturn" across the top and attach a state ment showing your income for the part of the year you were a nonresident. You can use form 1040NR as the statement; Enter "Dual-satus Satement" across the top. File your return and statement with Internal Revenue Service Center, Philadelpia, PA 19255, U.SA

If you were a noneresident......
similar to above, file 1040NR, attache 1040 as statement.