Morton N E, Simpson S P, Lew R, Yee S
Tissue Antigens. 1983 Oct;22(4):257-62. doi: 10.1111/j.1399-0039.1983.tb01201.x.
Maximum likelihood estimates of haplotype frequencies in multilocus systems are often zero and so may be genetically inacceptable. Estimation problems are discussed, and preferable estimates are derived.