The 1956 UST set is beautiful. They are engraved.
Then in 1971 another UST set was printed, to commemorate the 100th anniversary of the Colleges of Medicine and Pharmacy.
1971 UST set on First Day Cover
The UST Colleges of Education and Science both celebrated their 50th anniversary in 1976, when another commemorative set was issued. I remember going to the Main Building (I was a Mechanical Engineering student then) and buying some sets which my meager allowance could afford.
In 1988, the UST Graduate School celebrated it's 50th anniversary and the Bureau of Post issue this single in sheets of 100 and mini sheet of 6.
1988 UST Graduate School mini sheet
This month, January 2011, a Block-of-4 set and a souvenir sheet were printed to commemorate UST's 400 anniversary.
2011 B/4 set and Souvenir Sheet
First Day Cover set