You can just run a search on some of these articles.
Goode, C.J., and others: A meta-analysis of effects of heparin flush and saline flush: quality and cost implications, Nurs Res 40(6):324-330, 1991.
Gyr P and others: Double blind comparison of heparin and saline flush solutions in maintenance of peripheral infusion devices, Pediatr Nurs 21(4):383-389, 366, 1995.
Hanrahan, K.S., Kleiber, C., and Fagan, C.: Evaluation of saline for IV locks in children, Pediatr Nurs 20(6):549-552, 1994.
+Heilskov J and others: A randomized trial of heparin and saline for maintaining intravenous locks in neonates, JSPN 3(3):111-116, 1998.
Kleiber, C., and others: Heparin vs. saline for peripheral IV locks in children, Pediatr Nurs 19:405-409, 1993.
+Kotter RW: Heparin vs saline for intermittent intravenous device maintenance in neonates, Neonat Network 15(6):43-47, 1966.
LeDuc K: Efficacy of normal saline solution versus heparin solution for maintaining patency of peripheral intravenous catheters in children, J Emerg Nurs 23(4):306-309, 1997.
+Lombardi TP and others: Efficacy of 0.9% sodium chloride injection with or without heparin sodium for maintaining patency of intravenous catheters in children, Clinical Pharm 7(11):832-836, 1988.
+McMullen, A., and others: Heparinized saline or normal saline as a flush solution in intermittent intravenous lines in infants and children, MCN 18(2):78-85, 1993.
*Mudge B, Forcier D, and Slattery MJ: Patency of 24-gauge peripheral intermittent infusion devices: a comparison of heparin and saline flush solutions, Pediatr Nurs 24(2):142-149, 1998.
+Nelson TJ & Graves SM: 0.9% sodium chloride injection with and without heparin for maintaining peripheral indwelling intermittent-infusion devices in infants, Am J Health-Syst Pharm 55:570-573, 1998.
+Paisley MK and others: The use of heparin and normal saline flushes in neonatal intravenous catheters, Pediatr Nurs 23(5):521-527, 1997.
Robertson J: Intermittent intravenous therapy: a comparison of two flushing solutions, Contemp Nurs 3(4):174-179, 1994.