tứ bảo 
the four precious writing materials (brush, ink, paper, slab) [ tứ ] : (1) four; (2) idea, though (in literature)
[ bảo ] : (1) to say, order, tell (someone to do something); (2) to insure; (3) to protect, guard; (4) precious, valuable
Most Common Compounds Set 1:
Most Common Compounds Set 2 :