Question : Insert Statement using values and select subquery

Hi..
I'm trying to do Insert statement using values and select query,
I have 5 tables:
- INVOICE Table: that has INVNO column as primary key,
- COMPANIES Table : that has CNO column as primary key,
- STUDENTS Table: that has SNO column as primary key and CNO Column as foreign key,
- INVOICED Table: that has INVNO, SNO and both of them are foreign key ,
- STUDCRS Table : that has SNO column as a foreign key

now I want to insert data into INVOICED Table using the following Statement:

INSERT INTO INVOICED(INVNO,SNO)VALUES(
1,(SELECT STUDCRS.SNO FROM STUDCRS
INNER JOIN STUDENTS ON STUDENTS.SNO = STUDCRS.SNO
INNER JOIN COMPANIES ON COMPANIES.CNO = STUDENTS.CNO
WHERE STUDCRS.CRSNO=1 AND STUDENTS.CNO=1))

but I'm facing this error:
ORA-01427: single-row subquery returns more than one row

this statement working if I try to insert one row, but its not working with multiple rows
how can I fix that

Answer : Insert Statement using values and select subquery

INSERT INTO INVOICED(INVNO,SNO)
SELECT 1, STUDCRS.SNO
FROM STUDCRS
  INNER JOIN STUDENTS ON STUDENTS.SNO = STUDCRS.SNO
  INNER JOIN COMPANIES ON COMPANIES.CNO = STUDENTS.CNO
WHERE STUDCRS.CRSNO=1
  AND STUDENTS.CNO=1