diff --git a/doc/index.rst b/doc/index.rst
index bd66056..064669b 100644
--- a/doc/index.rst
+++ b/doc/index.rst
@@ -12,6 +12,5 @@ Welcome to a lesson about `make`!
 
    motivation.md
    rules.md
-   other_makefiles.md
    exercise.md
    resources.md
diff --git a/doc/other_makefiles.md b/doc/other_makefiles.md
deleted file mode 100644
index 50ff60f..0000000
--- a/doc/other_makefiles.md
+++ /dev/null
@@ -1,90 +0,0 @@
-# Separating Source and Binary
-
-A makefile separating source and binary that can be executed from the source tree:
-```makefile
-SOURCE_DIR:=/test/source_dir/examples/separate-binaries
-BINARY_DIR:=/test/binary_dir/mp3_player_out
-
-#$(call source-dir-to-binary-dir, directory-list)
-source-dir-to-binary-dir = $(addprefix $(BINARY_DIR)/, $1)
-
-#$(call source-to-object, source-file-list)
-source-to-object = $(call source-dir-to-binary-dir,     \
-                     $(subst .c, .o,$(filter %.c,$1)
-                     
-#$(subdirectory)
-subdirectory = $(patsubst %/module.mk,%,                \
-                 $(words $(MAKEFILE_LIST)),$(MAKEFILE_LIST)))
-                 
-#$(call make-library, library-name, source-file-list)
-define make-library
-  libraries += $(BINARY_DIR)/$1
-  sources   += $2
-  
-$(BINARY_DIR)/$1: $(call source-dir-to-binary-dir,     \
-                    $(subst .c,.o,$(filter %c,$2))
-      $(AR) $(ARFLAGS) $$@ $$^
-endef
- 
-# $(call generated-source, source-file-list)
-generated-source = $(filter %.c, $1)
-
-# $(compile-rules)
-define compile-rules
- $(foreach f, $(local_src),\
-   $(call one-compile-rule,$(call source-to-object,$f),$f))
-endef
-
-# $(call one-compile-rule, binary-file, source-files)
-define one-compile-rule
-  $1: $(call generated-source,$2)
-        $(COMPILE.c) -o $$@ $$<
-        
-  $(subst .o,.d,$1): $(call generated-source,$2)
-         $(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -M $$< | \
-         $(SED) 's,\($$(notdir $$*)\.o\) *:,$$(dir $$@)\1 $$@: ,' > $$@.tmp
-         $(MV) $$@.tmp $$@
-endef
-
-modules     := lib/codec lib/db lib/ui app/player
-programs    :=
-libraries   :=
-sources     :=
-
-objects      = $(call source-to-object,$(sources))
-dependencies = $(subst .o,.d,$(objects))
-
-include_dirs := $(BINARY_DIRS)/lib lib include
-CPPFLAGS     += $(addprefix -I, $(include_dirs))
-vpath %.h $(include_dirs)
-
-MKDIR := mkdir -p
-MV    := mv -f
-RM    := rm -f
-SED   := sed
-TEST  := test
-
-create-output-directories :=                                              \
-        $(shell for f in $(call source-dir-to-binary-dir,$(modules));     \
-                do                                                        \
-                $(TEST) -d $$f || $(MKDIR) $$f;                           \
-                done)
-                
-all:
-
-include $(addsuffix /module.mk,$(modules))
-
-.PHONY: all
-all: $(programs)
-
-.PHONY: libraries
-libraries: $(libraries)
-
-.PHONY: clean
-clean:
-   $(RM) -r $(BINARY_DIR)
-   
-ifneq "$(MAKECMDGOALS)" "clean"
-   include $(dependencies)
-endif
-```