Author　direct　citation　analysis　(ADCA,　also　called　inter-citation　or　cross　citation)　is　a　new　feasible　and　applicable　technique　for　exploring　knowledge　communication　and　discovering　scientific　structure.　This　study　explored　ADCA　among　prolific,　highly　cited,　and　core　authors　in　information　science　in　China　and　around　the　world.　The　results　revealed　the　following.　(1)　The　datasets　in　China　and　around　the　world　cover　overlapping,　but　also　unique　topics.　Research　subjects　on　information　science　around　the　world　can　be　divided　into　three　categories　and　10　clusters;　meanwhile,　that　in　China　can　be　divided　into　three　categories　and　9　clusters.　Chinese　scholars　who　are　mostly　involved　in　cross　subjects　and　multi-fields　are　not　as　specialized　and　profound　as　foreign　scholars.　An　obvious　imbalance　exists　in　the　evolution　of　discipline　structure　around　the　world,　indicating　the　necessity　of　a　synchronous　promotion　of　research　specialty　and　cross　comprehensiveness.　Chinese　scholars　concentrate　more　on　topics　such　as　competitive　intelligence,　information　resource　management,　and　information　retrieval,　and　they　focus　less　on　information　security　and　user　analysis.　(2)　Knowledge　communication　between　active　authors　is　stronger　than　the　knowledge　flow　from　highly　influential　authors　to　active　authors　around　the　world;　meanwhile,　Chinese　researchers　tend　to　adopt　the　knowledge　of　authoritative　literature.　The　knowledge　flow　through　bidirectional　direct　citation　is　related　to　mutual　knowledge　communication.　Authoritative　scholars　are　produced　when　prolific　authors　cite　highly　cited　authors.　The　level　of　mutual　recognition　among　Chinese　scholars　has　not　reached　that　among　foreign　scholars;　in　the　former,　less　bidirectional　flow　of　knowledge　is　involved,　and　unidirectional　flow　is　limited　to　geographical　proximity,　cooperation,　or　teacher-student　relationship.　(3)　In　contrast　to　traditional　author　co-citation　analysis　(ACA),　ADCA　pays　more　attention　to　the　mutual　interaction　among　currently　active　scholars　and　to　mainly　showing　the　current　research　focus.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.