Debiprasad Ghatak, Krishan Kumar Tyagi and Eshna Tiwari 2017. Implant placement in posterior atrophic maxilla using direct and indirect sinus augmentation- a comparative study. Asian Pacific Journal of Health Sciences. 4, 1 (Mar. 2017), 201–216. DOI:https://doi.org/10.21276/apjhs.2017.4.1.32.