CREATE TABLE table_101336_1 (crystal_structure VARCHAR, formula VARCHAR)

What is the crystal structure for the formula yba 2 cu 3 o 7?
SELECT crystal_structure FROM table_101336_1 WHERE formula = "YBa 2 Cu 3 O 7"
SELECT "crystal_structure" FROM "table_101336_1" WHERE "YBa 2 Cu 3 O 7" = "formula"