[1] Burke, D. K.: 
Covering properties. Handbook of Set-Theoretic Topology K. Kunen, J. E. Vaughan Elsevier Science Publishers (1984), 347-422. 
MR 0776628 | 
Zbl 0569.54022[6] Engelking, R. R.: 
General Topology. Revised and completed edition. Heldermann Berlin (1989). 
MR 1039321[10] Lutzer, D. J.: 
On generalized Ordered Spaces. Dissertationes Math. Vol. 89. (1971). 
MR 0324668[13] Steen, L. A., Seebach, J. A.: 
Counterexamples in Topology. Springer-Verlag New York (1978). 
MR 0507446 | 
Zbl 0386.54001