diff --git a/src/userland/scisi/main.c b/src/userland/scisi/main.c
index e6abe97..b77f31e 100644
--- a/src/userland/scisi/main.c
+++ b/src/userland/scisi/main.c
@@ -3,6 +3,8 @@
 
 ListElement *devices = NULL;
 
+// see https://www.seagate.com/files/staticfiles/support/docs/manual/Interface%20manuals/100293068j.pdf
+
 void doInquiry(ScisiDevice *device) {
     InquiryCommand *command = malloc(sizeof(InquiryCommand));
     command->size = sizeof(InquiryCommand) - 2*sizeof(uint32_t);

diff --git a/src/userland/scisi/main.c b/src/userland/scisi/main.c
index e6abe97..b77f31e 100644
--- a/src/userland/scisi/main.c
+++ b/src/userland/scisi/main.c
@@ -3,6 +3,8 @@
 
 ListElement *devices = NULL;
 
+// see https://www.seagate.com/files/staticfiles/support/docs/manual/Interface%20manuals/100293068j.pdf
+
 void doInquiry(ScisiDevice *device) {
     InquiryCommand *command = malloc(sizeof(InquiryCommand));
     command->size = sizeof(InquiryCommand) - 2*sizeof(uint32_t);
diff --git a/src/userland/usbStorage/main.c b/src/userland/usbStorage/main.c
index 0a3ebff..746b46b 100644
--- a/src/userland/usbStorage/main.c
+++ b/src/userland/usbStorage/main.c
@@ -1,6 +1,9 @@
 #include <storage.h>
 #include <hlib.h>
 
+// mass storage: https://www.usb.org/sites/default/files/Mass_Storage_Specification_Overview_v1.4_2-19-2010.pdf
+// bulk only: https://www.usb.org/sites/default/files/usbmassbulk_10.pdf
+
 typedef union {
     uint32_t value;
     struct {