halim l., abdullah s.i.s.s., meerah t.s.m..  (2014).  students' perceptions of their science teachers' pedagogical content knowledge.  - journal of science education and technology.  227 - 237. 

lilia halim, sharifah intan sharina syed abdullah, t subahan meerah.  (2014).  students` perception of their science teachers` pedagogical content knowledge.  - journal of science education and technology.  23(2):227-237.