  We studied eight new doubly eclipsing stellar systems. We found that they are
all rare examples of quadruple systems of 2 + 2 architecture, where both inner
pairs are eclipsing binaries. Until now, such a configuration had only been
proven for dozens of systems on the whole sky. We enlarged this rare group of
systems with four stars in the Small Magellanic Cloud (SMC) galaxy and four
brighter stars on the northern sky. These analysed systems are the following:
OGLE SMC-ECL-2339 (both eclipsing periods of 0.72884 days and 3.39576 days;
mutual orbital period of 5.95 years); OGLE SMC-ECL-3075 (1.35890 d, 2.41587 d,
9.75 yr); OGLE SMC-ECL-4756 (0.91773 d, 2.06047 d, 4.34 yr); OGLE SMC-ECL-6093
(0.90193 d, 2.03033 d, 31.2 yr); GSC 01949-01700 (0.24058 d, 0.75834 d, 21.7
yr); ZTF J171602.61+273606.5 (0.36001 d, 4.51545 d, 19.5 yr); WISE
J210935.8+390501 (0.33228 d, 3.51575 d, 1.9 yr); and V597 And (0.46770 d,
0.35250, 20.4 yr). These systems constitute a rare selection of W UMa stars
among the doubly eclipsing quadruples. For all of the systems, new dedicated
observations were obtained as well. V597 And is definitely the most interesting
system for several reasons: (1) the system is the brightest in our sample; (2)
it is a rare quintuple (2 + 2) + 1 system; and (3) it is also closest to the
Sun. It yielded the predicted angular separation of the two components of 57
mas, which is probably within the detection limits for modern,
high-angular-resolution techniques.
