NGA. Geodetic Calculator.
http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm96/intpt.html

has been cited by the following article:

• TITLE: Geodetic Datum Transformation Parameters towards WGS84 Applicable to the 1/50k Topographical Map (1981) of Burundi

  AUTHORS: Johan Lavreau

  KEYWORDS: Geodesy, Cartography, Datum Calculation, Burundi

  JOURNAL NAME: International Journal of Geosciences, Vol.7 No.5, May 17, 2016

  ABSTRACT: The knowledge of the geodetic reference datum of maps or data is required for their use in a GIS. Many older maps are lacking this information, making their use cumbersome. The availability of an aerial coverage at high resolution of Burundi and digital elevation model, based on a novel geodetic network, all calculated on the WGS84 datum, allows to calculate the datum applicable to older maps, for instance the regular 1/50k map of the country. The method, based on the difference in geocentric coordinates between points common to the two systems, yields: Δx = -156.71 ± 10.2 m, .Δy = -3.26 ± 13.2 m, .Δz = -290.77 ± 21.06 m, well in keeping with older values proposed by the NGA.