**Table 3:** Summary of the two observational samples.
Sample name	FSM	IRAS
Number of IR sources:
- initial IR photometric sample	24	38
- optical identifications and redshifts	26	28
- with ${\rm H}\alpha$ emission line	23	21

Comments: three IR sources (two in the FSM sample and one in the IRAS sample) have been split into two optical objects.