  The light-time effect method, its limitations and applications were studied.
A powerful combined method of simultaneous analysis of the O-C diagrams and
astrometric orbit in triple eclipsing-astrometric binaries was presented.
Eleven eclipsing systems were studied in detail according to their O-C diagrams
(RY Aqr, BF CMi, RW Cap, TY Cap, SS Cet, RR Dra, TY Del, TZ Eri, RV Per, UZ
Sge, and BO Vul). The introduced method for studying the astrometric-eclipsing
binaries was applied to QS Aql, VW Cep, Zeta Phe, V505 Sgr, HT Vir, and V2388
Oph. The algorithm for such an analysis was introduced and the its limitations
were discussed. The catalogue of another systems, which contain eclipsing
binaries in astrometric binaries, was presented. Such systems could be useful
for prospective analysis. The method itself could be easily modified for
estimation of the parallax of the individual systems.
