@article{10_1017_S0017089510000595,
     author = {LI, TIEQIANG and SCH\"UTZ, DIRK},
     title = {ON {THE} {RELATIVE} {LUSTERNIK{\textendash}SCHNIRELMANN} {CATEGORY} {WITH} {RESPECT} {TO} {A} {REAL} {COHOMOLOGY} {CLASS}},
     journal = {Glasgow mathematical journal},
     pages = {169--183},
     year = {2011},
     volume = {53},
     number = {1},
     doi = {10.1017/S0017089510000595},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089510000595/}
}