sql>create table p (c1 int, c2 int, primary key (c1, c2));
 
Table created.
 
sql>create table c (x int, c1 int, c2 int, foreign key (c1, c2) references p);
 
Table created.

SQL> ed
Wrote file afiedt.buf

  1  CREATE TABLE parent
  2  (
  3  year NUMBER(4) ,
  4  month NUMBER(2),
  5* constraint p_parent PRIMARY KEY  (year,month))
SQL> /

Table created.
SQL> ed
Wrote file afiedt.buf

  1  CREATE TABLE child
  2  (
  3  id VARCHAR2(7),
  4  year NUMBER(4),
  5  month NUMBER(2),
  6  constraint fk_child FOREIGN KEY (year, month)
  7* REFERENCES parent(year,month ))
SQL> /

Table created.