Bull. Math. Soc. Sci. Math. Roumanie 
Carol Zamfirescu:
Acute triangulations of the double triangle, p.189-193
 Up: TOME 47 (95), no. 3-4
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Abstract:
We prove that every doubly covered triangle can be triangulated with 12 
acute triangles, and this number is best possible.
Key Words: Geodesic triangulations, acute triangles.
2000 Mathematics Subject Classification: Primary: 52B12, 
Secondary: 52C20.