Problem with linking : Error: L6218E: Undefined symbols

Hello,

I created a project on STM32F407ZET6 with Keil µVision V5 14.0.0.

When build project I have these errors:

compiling main.c...
compiling os_app_hooks.c...
linking...
.\Flash\Obj\output.axf: Error: L6218E: Undefined symbol UART1_Init (referred from bsp.o).
.\Flash\Obj\output.axf: Error: L6218E: Undefined symbol UART3_Init (referred from bsp.o).
.\Flash\Obj\output.axf: Error: L6218E: Undefined symbol UART1_RxDMA_ReceiveLeftStr (referred from main.o).
Not enough information to list image symbols.
Finished: 1 information, 0 warning and 3 error messages.
".\Flash\Obj\output.axf" - 3 Error(s), 3 Warning(s).
Target not created.
Build Time Elapsed: 00:00:33

I have included .h files, and added .c files to project group.

Thanks!