[1] ARHANGEL'SKII A. V.: 
Bicompacta that satisfy the Suslin condition hereditarily. Tightness and free sequences. Soviet Math. Dokl. 12 (1971), 1253-1257. 
MR 0288718[2] ARHANGEL'SKII A. V.: 
Structure and classification of topological spaces and cardinal invariants. Russian Math. Surveys 33 (1978), 33-95. 
MR 0526012[3] ARHANGEL'SKII A. V., ISLER R., TIRONI G.: 
On pseudo-radial spaces. this issue, 137-154. 
MR 0843426[4] ARHANGEL'SKII A. V., ISLER R., TIRONI G.: 
Pseudo-radial spaces and on other generalization of sequential spaces. to appear in Proc. of Conf. on Convergence, Bechyně (Czechoslovakia) 1984, Akademie Verlag, Berlin. 
MR 0835468[6] FROLÍK Z., ISLER R., TIRONI G.: Some results on chain net and sequential spaces. Coll. Soc. Math. J. Bolyai 41, Topology and applications.
[7] HERRLICH H.: 
Quotienten geordneter Räume und Folgenkonvergenz. Fund. Math. 61 (1967), 79-81. 
MR 0221476 | 
Zbl 0158.41103[8] JANÉ I., MEYER P. R., SIMON P., WILSON R. G.: 
On tightness in chain-net spaces. Comment. Math. Univ. Carolinae 22 (1981), 809-817. 
MR 0647028[9] JUHÁSZ I.: 
Cardinal Functions in Topology: Ten years later. Math. Centre Tracts 123, Amsterdam (1980). 
MR 0576927[10] TIRONI G.: 
Some remarks on radial and pseudo-radial spaces. Proc. Fifth Prague Topol. Symp. 1981, Helderman, Berlin, 1982, 608-612. 
MR 0698465