Routines to convert equatorial coordinates to Solar Ecliptic Coordinate System

Dear all,
coudl someone tell me a website (or a book) where I can find how to
convert from equatorial
coordinates to projection vectors along the solar ecliptic coordinates
(where solar ecliptic
coordinatea are defined in (1) of
http://cohoweb.gsfc.nasa.gov/helios/plan_des.html)

Thanks
Melroy

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