@article{JOLT_2015_25_2_a3,
     author = {N. Abe},
     title = {First extension groups of {Verma} modules and {R-polynomials}},
     journal = {Journal of Lie Theory},
     pages = {377--393},
     year = {2015},
     volume = {25},
     number = {2},
     doi = {10.5802/jolt.841},
     zbl = {1394.17014},
     url = {https://jolt.centre-mersenne.org/articles/10.5802/jolt.841/}
}