The theorems of LOCATION@1 , PERSON@1 and PERSON@2 on quadrilaterals , including the PERSON@3 -- PERSON@4 quadrilateral and PERSON@1 -- PERSON@5 quadrilateral , were the first theorems on hyperbolic geometry .

The theorems of LOCATION@1 , PERSON@1 on quadrilaterals , were the first theorems on hyperbolic geometry .
